ElPiedra muchas gracias por tu ayuda. He hecho todo lo que me has pedido, pero sigo teniendo problemas :
Cuando le doy a a la entrada:
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = about-blank.in
me vuelve a salir como si no la hubiera quitado al reiniciar mi PC, una otra vez, volviendo así a la página de inicio ( http://www.portaldeayuda.tv/buscador/ )
Y, ahora, cada vez que reinicio, mi escritorio sale en un fondo azul con los accesos directos a programas desordenados.
Sin más pego reportes:

--------------------REPORTE DE HJT---------

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 22:41:02, on 31/08/2007
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP2 (6.00.2900.2180)
Boot mode: Normal

Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Intel\Wireless\Bin\EvtEng.exe
C:\Program Files\Intel\Wireless\Bin\S24EvMon.exe
C:\WINDOWS\system32\spoolsv.exe
c:\program files\common files\logitech\lvmvfm\LVPrcSrv.exe
C:\Program Files\AntiVir PersonalEdition Classic\avguard.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\rundll32.exe
C:\WINDOWS\ehome\ehtray.exe
C:\WINDOWS\RTHDCPL.EXE
C:\Program Files\Synaptics\SynTP\SynTPEnh.exe
C:\WINDOWS\eHome\ehmsas.exe
C:\Acer\Empowering Technology\admtray.exe
C:\Acer\Empowering Technology\eDataSecurity\eDSloader.exe
C:\Acer\Empowering Technology\ePower\ePower_DMC.exe
C:\PROGRA~1\LAUNCH~1\LManager.exe
C:\Program Files\AntiVir PersonalEdition Classic\sched.exe
C:\Acer\Empowering Technology\eRecovery\Monitor.exe
C:\WINDOWS\system32\LVCOMSX.EXE
C:\Program Files\Grisoft\AVG Anti-Spyware 7.5\guard.exe
C:\WINDOWS\system32\ElkCtrl.exe
C:\Program Files\Java\jre1.6.0_01\bin\jusched.exe
C:\Program Files\Acer\OrbiCam\CameraAssistant.exe
C:\Program Files\Common Files\Symantec Shared\PIF\{B8E1DD85-8582-4c61-B58F-2F227FCA9A08}\PIFSvc.exe
C:\Acer\Empowering Technology\admServ.exe
C:\Program Files\Google\Gmail Notifier\gnotify.exe
C:\Program Files\AntiVir PersonalEdition Classic\avgnt.exe
C:\Program Files\Grisoft\AVG Anti-Spyware 7.5\avgas.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Program Files\Macrogaming\SweetIM\SweetIM.exe
C:\Program Files\Ares\Ares.exe
C:\Program Files\MSN Messenger\msnmsgr.exe
C:\WINDOWS\system32\bmwebcfg.exe
c:\Program Files\WIDCOMM\Bluetooth Software\bin\btwdins.exe
C:\WINDOWS\eHome\ehRecvr.exe
C:\Program Files\SUPERAntiSpyware\SUPERAntiSpyware.exe
C:\WINDOWS\eHome\ehSched.exe
C:\Program Files\WIDCOMM\Bluetooth Software\BTTray.exe
C:\Program Files\Common Files\LightScribe\LSSrvc.exe
C:\Program Files\Common Files\Symantec Shared\PIF\{B8E1DD85-8582-4c61-B58F-2F227FCA9A08}\PIFSvc.exe
C:\WINDOWS\system32\nvsvc32.exe
C:\Program Files\Symantec\LiveUpdate\ALUSchedulerSvc.exe
C:\Program Files\Intel\Wireless\Bin\RegSrvc.exe
C:\WINDOWS\system32\svchost.exe
C:\DOCUME~1\MARYCO~1\LOCALS~1\Temp\RtkBtMnt.exe
C:\WINDOWS\system32\dllhost.exe
C:\Program Files\Trend Micro\HijackThis\HijackThis.exe
C:\Program Files\MessengerDiscovery\MessengerDiscovery Live.exe
C:\WINDOWS\system32\wbem\unsecapp.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = about-blank.in
R1 - HKCU\Software\Microsoft\Internet Connection Wizard,ShellNext = http://www.google.es/
R3 - URLSearchHook: Yahoo! Toolbar - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - (no file)
O2 - BHO: Adobe PDF Reader Link Helper - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Adobe\Acrobat 7.0\ActiveX\AcroIEHelper.dll
O2 - BHO: (no name) - {53707962-6F74-2D53-2644-206D7942484F} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre1.6.0_01\bin\ssv.dll
O2 - BHO: (no name) - {7E853D72-626A-48EC-A868-BA8D5E23E045} - (no file)
O2 - BHO: Windows Live Sign-in Helper - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Program Files\Common Files\Microsoft Shared\Windows Live\WindowsLiveLogin.dll
O2 - BHO: Google Toolbar Helper - {AA58ED58-01DD-4d91-8333-CF10577473F7} - c:\program files\google\googletoolbar1.dll
O2 - BHO: Google Toolbar Notifier BHO - {AF69DE43-7D58-4638-B6FA-CE66B5AD205D} - C:\Program Files\Google\GoogleToolbarNotifier\2.0.301.5672\sw g.dll
O3 - Toolbar: Acer eDataSecurity Management - {5CBE3B7C-1E47-477e-A7DD-396DB0476E29} - C:\WINDOWS\system32\eDStoolbar.dll
O3 - Toolbar: &Google - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - c:\program files\google\googletoolbar1.dll
O4 - HKLM\..\Run: [igfxtray] C:\WINDOWS\system32\igfxtray.exe
O4 - HKLM\..\Run: [igfxhkcmd] C:\WINDOWS\system32\hkcmd.exe
O4 - HKLM\..\Run: [igfxpers] C:\WINDOWS\system32\igfxpers.exe
O4 - HKLM\..\Run: [BluetoothAuthenticationAgent] rundll32.exe bthprops.cpl,,BluetoothAuthenticationAgent
O4 - HKLM\..\Run: [ehTray] C:\WINDOWS\ehome\ehtray.exe
O4 - HKLM\..\Run: [LaunchApp] Alaunch
O4 - HKLM\..\Run: [RTHDCPL] RTHDCPL.EXE
O4 - HKLM\..\Run: [SkyTel] SkyTel.EXE
O4 - HKLM\..\Run: [Alcmtr] ALCMTR.EXE
O4 - HKLM\..\Run: [AzMixerSel] C:\Program Files\Realtek\InstallShield\AzMixerSel.exe
O4 - HKLM\..\Run: [SynTPEnh] C:\Program Files\Synaptics\SynTP\SynTPEnh.exe
O4 - HKLM\..\Run: [ntiMUI] C:\Program Files\NewTech Infosystems\NTI CD & DVD-Maker 7\ntiMUI.exe
O4 - HKLM\..\Run: [ADMTray.exe] "C:\Acer\Empowering Technology\admtray.exe"
O4 - HKLM\..\Run: [eDataSecurity Loader] C:\Acer\Empowering Technology\eDataSecurity\eDSloader.exe
O4 - HKLM\..\Run: [IMJPMIG8.1] "C:\WINDOWS\IME\imjp8_1\IMJPMIG.EXE" /Spoil /RemAdvDef /Migration32
O4 - HKLM\..\Run: [MSPY2002] C:\WINDOWS\system32\IME\PINTLGNT\ImScInst.exe /SYNC
O4 - HKLM\..\Run: [PHIME2002ASync] C:\WINDOWS\system32\IME\TINTLGNT\TINTSETP.EXE /SYNC
O4 - HKLM\..\Run: [PHIME2002A] C:\WINDOWS\system32\IME\TINTLGNT\TINTSETP.EXE /IMEName
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [nwiz] nwiz.exe /install
O4 - HKLM\..\Run: [NvMediaCenter] RUNDLL32.EXE C:\WINDOWS\system32\NvMcTray.dll,NvTaskbarInit
O4 - HKLM\..\Run: [ePower_DMC] C:\Acer\Empowering Technology\ePower\ePower_DMC.exe
O4 - HKLM\..\Run: [Acer ePower Management] C:\Acer\Empowering Technology\ePower\Acer ePower Management.exe boot
O4 - HKLM\..\Run: [LManager] C:\PROGRA~1\LAUNCH~1\LManager.exe
O4 - HKLM\..\Run: [eRecoveryService] C:\Acer\Empowering Technology\eRecovery\Monitor.exe
O4 - HKLM\..\Run: [LVCOMSX] C:\WINDOWS\system32\LVCOMSX.EXE
O4 - HKLM\..\Run: [LogitechVideo[inspector]] C:\Program Files\Acer\OrbiCam\InstallHelper.exe /inspect
O4 - HKLM\..\Run: [LogitechCameraService(E)] C:\WINDOWS\system32\ElkCtrl.exe /automation
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Java\jre1.6.0_01\bin\jusched.exe"
O4 - HKLM\..\Run: [LogitechCameraAssistant] C:\Program Files\Acer\OrbiCam\CameraAssistant.exe
O4 - HKLM\..\Run: [Symantec PIF AlertEng] "C:\Program Files\Common Files\Symantec Shared\PIF\{B8E1DD85-8582-4c61-B58F-2F227FCA9A08}\PIFSvc.exe" /a /m "C:\Program Files\Common Files\Symantec Shared\PIF\{B8E1DD85-8582-4c61-B58F-2F227FCA9A08}\AlertEng.dll"
O4 - HKLM\..\Run: [{0228e555-4f9c-4e35-a3ec-b109a192b4c2}] C:\Program Files\Google\Gmail Notifier\gnotify.exe
O4 - HKLM\..\Run: [SweetIM] C:\Program Files\Macrogaming\SweetIM\SweetIM.exe
O4 - HKLM\..\Run: [avgnt] "C:\Program Files\AntiVir PersonalEdition Classic\avgnt.exe" /min
O4 - HKLM\..\Run: [!AVG Anti-Spyware] "C:\Program Files\Grisoft\AVG Anti-Spyware 7.5\avgas.exe" /minimized
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [msnmsgr] ~"C:\Program Files\MSN Messenger\msnmsgr.exe" /background
O4 - HKCU\..\Run: [SweetIM] C:\Program Files\Macrogaming\SweetIM\SweetIM.exe
O4 - HKCU\..\Run: [ares] "C:\Program Files\Ares\Ares.exe" -h
O4 - HKCU\..\Run: [SUPERAntiSpyware] C:\Program Files\SUPERAntiSpyware\SUPERAntiSpyware.exe
O4 - HKUS\S-1-5-18\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SYSTEM')
O4 - HKUS\.DEFAULT\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'Default user')
O4 - Global Startup: BTTray.lnk = ?
O4 - Global Startup: Start Winks & Moods Messenger.lnk = C:\Program Files\Winks Instalador\msngserv.exe
O6 - HKCU\Software\Policies\Microsoft\Internet Explorer\Control Panel present
O6 - HKLM\Software\Policies\Microsoft\Internet Explorer\Restrictions present
O8 - Extra context menu item: Enviar a &Bluetooth - c:\Program Files\WIDCOMM\Bluetooth Software\btsendto_ie_ctx.htm
O10 - Unknown file in Winsock LSP: bmnet.dll
O10 - Unknown file in Winsock LSP: bmnet.dll
O10 - Unknown file in Winsock LSP: bmnet.dll
O16 - DPF: {0EB0E74A-2A76-4AB3-A7FB-9BD8C29F7F75} (CKAVWebScan Object) - http://www.kaspersky.com/kos/eng/partner/default/kavwebscan_unicode.cab
O16 - DPF: {193C772A-87BE-4B19-A7BB-445B226FE9A1} (ewidoOnlineScan Control) - http://downloads.ewido.net/ewidoOnlineScan.cab
O16 - DPF: {30528230-99f7-4bb4-88d8-fa1d4f56a2ab} (YInstStarter Class) - C:\Program Files\Yahoo!\Common\yinsthelper.dll
O16 - DPF: {A8739816-022C-11D6-A85D-00C04F9AEAFB} (Web Camera Server Control) - http://www.uoct.cl/uoct/repositorio/wg_webeye.cab
O16 - DPF: {BD8667B7-38D8-4C77-B580-18C3E146372C} (Creative Toolbox Plug-in) - http://ak.imgag.com/imgag/cp/install/Crusher.cab
O20 - Winlogon Notify: !SASWinLogon - C:\Program Files\SUPERAntiSpyware\SASWINLO.DLL
O23 - Service: AntiVir PersonalEdition Classic Scheduler (AntiVirScheduler) - Avira GmbH - C:\Program Files\AntiVir PersonalEdition Classic\sched.exe
O23 - Service: AntiVir PersonalEdition Classic Guard (AntiVirService) - Avira GmbH - C:\Program Files\AntiVir PersonalEdition Classic\avguard.exe
O23 - Service: Ares Chatroom server (AresChatServer) - Ares Development Group - C:\Program Files\Ares\chatServer.exe
O23 - Service: AVG Anti-Spyware Guard - GRISOFT s.r.o. - C:\Program Files\Grisoft\AVG Anti-Spyware 7.5\guard.exe
O23 - Service: AdminWorks Agent X6 (AWService) - Avocent Inc. - C:\Acer\Empowering Technology\admServ.exe
O23 - Service: Bytemobile Web Configurator (bmwebcfg) - Bytemobile, Inc. - C:\WINDOWS\system32\bmwebcfg.exe
O23 - Service: Bluetooth Service (btwdins) - Broadcom Corporation. - c:\Program Files\WIDCOMM\Bluetooth Software\bin\btwdins.exe
O23 - Service: Intel(R) PROSet/Wireless Event Log (EvtEng) - Intel Corporation - C:\Program Files\Intel\Wireless\Bin\EvtEng.exe
O23 - Service: Google Updater Service (gusvc) - Google - C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe
O23 - Service: InstallDriver Table Manager (IDriverT) - Macrovision Corporation - C:\Program Files\Common Files\InstallShield\Driver\11\Intel 32\IDriverT.exe
O23 - Service: LightScribeService Direct Disc Labeling Service (LightScribeService) - Hewlett-Packard Company - C:\Program Files\Common Files\LightScribe\LSSrvc.exe
O23 - Service: LiveUpdate - Symantec Corporation - C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
O23 - Service: LiveUpdate Notice Service - Symantec Corporation - C:\Program Files\Common Files\Symantec Shared\PIF\{B8E1DD85-8582-4c61-B58F-2F227FCA9A08}\PIFSvc.exe
O23 - Service: Logitech Process Monitor (LVPrcSrv) - Logitech - c:\program files\common files\logitech\lvmvfm\LVPrcSrv.exe
O23 - Service: NVIDIA Display Driver Service (NVSvc) - NVIDIA Corporation - C:\WINDOWS\system32\nvsvc32.exe
O23 - Service: Programador de LiveUpdate automático - Symantec Corporation - C:\Program Files\Symantec\LiveUpdate\ALUSchedulerSvc.exe
O23 - Service: Intel(R) PROSet/Wireless Registry Service (RegSrvc) - Intel Corporation - C:\Program Files\Intel\Wireless\Bin\RegSrvc.exe
O23 - Service: Remote Packet Capture Protocol v.0 (experimental) (rpcapd) - CACE Technologies - C:\Program Files\WinPcap\rpcapd.exe
O23 - Service: Intel(R) PROSet/Wireless Service (S24EventMonitor) - Intel Corporation - C:\Program Files\Intel\Wireless\Bin\S24EvMon.exe

--
End of file - 11397 bytes
--------------------------------------------
------REPORTE DE DelPSGuard-------------------
--------------------------------------------
DelPSGuard v 4.6.5
by www.ForoSpyware.com
Escaneo a las: 22:42:03,64, 31/08/2007
SO: Microsoft Windows XP [Versi¢n 5.1.2600]


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Un saludo.