No te preocupes, ElPiedra. Se solucionó el problema de la velocidad de Internet, y el ordenador aparece desinfectado en teoría. Es sólo que el UAC (User Account Control) aparece habilitado y es imposible deshabilitarlo, cuando antes era posible habilitarlo y deshabilitarlo cuando quisieras. No sé si alguna otra cosa se habrá quedado tocada después del arreglo, en estos tres días no he notado nada más.
Aquí te dejo el informe del HijackThis:

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 12:48:37, on 15/08/2008
Platform: Windows Vista SP1 (WinNT 6.00.1905)
MSIE: Internet Explorer v7.00 (7.00.6001.18000)
Boot mode: Normal

Running processes:
C:\Windows\system32\taskeng.exe
C:\Windows\system32\Dwm.exe
C:\Windows\Explorer.EXE
C:\Program Files\Synaptics\SynTP\SynTPEnh.exe
C:\Program Files\Motorola\SMSERIAL\sm56hlpr.exe
C:\Windows\RtHDVCpl.exe
C:\Program Files\Intel\Intel Matrix Storage Manager\IAAnotif.exe
C:\Program Files\HP\QuickPlay\QPService.exe
C:\Program Files\Hewlett-Packard\HP Quick Launch Buttons\QLBCTRL.exe
C:\Program Files\Hewlett-Packard\HP QuickTouch\HPKBDAPP.exe
C:\Program Files\HP\Digital Imaging\bin\HpqSRmon.exe
C:\Program Files\HP\HP Software Update\hpwuSchd2.exe
C:\Program Files\Hewlett-Packard\HP Wireless Assistant\HPWAMain.exe
C:\Program Files\Hewlett-Packard\HP Wireless Assistant\WiFiMsg.exe
C:\Program Files\Java\jre1.6.0_02\bin\jusched.exe
C:\Program Files\ESET\ESET NOD32 Antivirus\egui.exe
C:\Windows\System32\igfxtray.exe
C:\Windows\System32\hkcmd.exe
C:\Windows\System32\igfxpers.exe
C:\Program Files\Elaborate Bytes\VirtualCloneDrive\VCDDaemon.exe
C:\Program Files\WIDCOMM\Bluetooth Software\BTTray.exe
C:\Windows\system32\igfxsrvc.exe
C:\Program Files\WIDCOMM\Bluetooth Software\BtStackServer.exe
C:\Program Files\Hewlett-Packard\Shared\HpqToaster.exe
C:\Program Files\Synaptics\SynTP\SynTPHelper.exe
C:\Program Files\Java\jre1.6.0_02\bin\jucheck.exe
C:\Program Files\Windows Live\Messenger\msnmsgr.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\Program Files\Trend Micro\HijackThis\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://es.yahoo.com/
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://go.microsoft.com/fwlink/?LinkId=69157
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = http://go.microsoft.com/fwlink/?LinkId=54896
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://ie.redirect.hp.com/svs/rdr?TYPE=3&tp=iehome&locale=en_es&c=81&bd=Pavilion &pf=laptop
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName =
O2 - BHO: Aplicación auxiliar de vínculos de Adobe PDF Reader - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelper.dll
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre1.6.0_02\bin\ssv.dll
O2 - BHO: (no name) - {7E853D72-626A-48EC-A868-BA8D5E23E045} - (no file)
O2 - BHO: Windows Live Aplicación auxiliar de inicio de sesión - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Program Files\Common Files\Microsoft Shared\Windows Live\WindowsLiveLogin.dll
O2 - BHO: HP Print Clips - {FFFFFFFF-FF12-44C5-91EC-068E3AA1B2D7} - c:\Program Files\HP\Smart Web Printing\hpswp_framework.dll
O4 - HKLM\..\Run: [SynTPEnh] C:\Program Files\Synaptics\SynTP\SynTPEnh.exe
O4 - HKLM\..\Run: [SMSERIAL] C:\Program Files\Motorola\SMSERIAL\sm56hlpr.exe
O4 - HKLM\..\Run: [RtHDVCpl] RtHDVCpl.exe
O4 - HKLM\..\Run: [IAAnotif] C:\Program Files\Intel\Intel Matrix Storage Manager\iaanotif.exe
O4 - HKLM\..\Run: [QPService] "C:\Program Files\HP\QuickPlay\QPService.exe"
O4 - HKLM\..\Run: [QlbCtrl] %ProgramFiles%\Hewlett-Packard\HP Quick Launch Buttons\QlbCtrl.exe /Start
O4 - HKLM\..\Run: [OnScreenDisplay] C:\Program Files\Hewlett-Packard\HP QuickTouch\HPKBDAPP.exe
O4 - HKLM\..\Run: [UCam_Menu] "C:\Program Files\CyberLink\YouCam\MUITransfer\MUIStartMenu.ex e" "C:\Program Files\CyberLink\YouCam" update "Software\CyberLink\YouCam\1.0"
O4 - HKLM\..\Run: [hpqSRMon] C:\Program Files\HP\Digital Imaging\bin\hpqSRMon.exe
O4 - HKLM\..\Run: [HP Software Update] C:\Program Files\Hp\HP Software Update\HPWuSchd2.exe
O4 - HKLM\..\Run: [hpWirelessAssistant] C:\Program Files\Hewlett-Packard\HP Wireless Assistant\HPWAMain.exe
O4 - HKLM\..\Run: [WAWifiMessage] C:\Program Files\Hewlett-Packard\HP Wireless Assistant\WiFiMsg.exe
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Java\jre1.6.0_02\bin\jusched.exe"
O4 - HKLM\..\Run: [egui] "C:\Program Files\ESET\ESET NOD32 Antivirus\egui.exe" /hide /waitservice
O4 - HKLM\..\Run: [IgfxTray] C:\Windows\system32\igfxtray.exe
O4 - HKLM\..\Run: [HotKeysCmds] C:\Windows\system32\hkcmd.exe
O4 - HKLM\..\Run: [Persistence] C:\Windows\system32\igfxpers.exe
O4 - HKLM\..\Run: [VirtualCloneDrive] "C:\Program Files\Elaborate Bytes\VirtualCloneDrive\VCDDaemon.exe" /s
O4 - HKLM\..\Run: [Adobe Reader Speed Launcher] "C:\Program Files\Adobe\Reader 8.0\Reader\Reader_sl.exe"
O4 - HKUS\S-1-5-19\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /detectMem (User 'LOCAL SERVICE')
O4 - HKUS\S-1-5-19\..\Run: [WindowsWelcomeCenter] rundll32.exe oobefldr.dll,ShowWelcomeCenter (User 'LOCAL SERVICE')
O4 - HKUS\S-1-5-20\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /detectMem (User 'NETWORK SERVICE')
O4 - Global Startup: Bluetooth.lnk = ?
O8 - Extra context menu item: E&xport to Microsoft Excel - res://C:\PROGRA~1\MICROS~3\Office12\EXCEL.EXE/3000
O8 - Extra context menu item: Send image to &Bluetooth Device... - C:\Program Files\WIDCOMM\Bluetooth Software\btsendto_ie_ctx.htm
O8 - Extra context menu item: Send page to &Bluetooth Device... - C:\Program Files\WIDCOMM\Bluetooth Software\btsendto_ie.htm
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.6.0_02\bin\ssv.dll
O9 - Extra 'Tools' menuitem: Sun Java Console - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.6.0_02\bin\ssv.dll
O9 - Extra button: HP Smart Select - {58ECB495-38F0-49cb-A538-10282ABF65E7} - c:\Program Files\HP\Smart Web Printing\hpswp_extensions.dll
O9 - Extra button: Research - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~3\Office12\REFIEBAR.DLL
O9 - Extra button: @btrez.dll,-4015 - {CCA281CA-C863-46ef-9331-5C8D4460577F} - C:\Program Files\WIDCOMM\Bluetooth Software\btsendto_ie.htm
O9 - Extra 'Tools' menuitem: @btrez.dll,-12650 - {CCA281CA-C863-46ef-9331-5C8D4460577F} - C:\Program Files\WIDCOMM\Bluetooth Software\btsendto_ie.htm
O13 - Gopher Prefix:
O16 - DPF: {2D8ED06D-3C30-438B-96AE-4D110FDC1FB8} - http://acs.pandasoftware.com/activescan/cabs/as2stubie.cab
O16 - DPF: {A2505C6C-6F17-456F-89D2-4301FBDC6EC7} - https://myoffice.deloitte.es/nortel_cacheable/iewiper.cab
O17 - HKLM\System\CCS\Services\Tcpip\..\{CC4054B2-4FA8-48A2-83F0-F841059831A7}: NameServer = 80.58.61.250,80.58.61.254
O23 - Service: Com4Qlb - Hewlett-Packard Development Company, L.P. - C:\Program Files\Hewlett-Packard\HP Quick Launch Buttons\Com4Qlb.exe
O23 - Service: Eset HTTP Server (EhttpSrv) - ESET - C:\Program Files\ESET\ESET NOD32 Antivirus\EHttpSrv.exe
O23 - Service: Eset Service (ekrn) - ESET - C:\Program Files\ESET\ESET NOD32 Antivirus\ekrn.exe
O23 - Service: HP Health Check Service - Hewlett-Packard - c:\Program Files\Hewlett-Packard\HP Health Check\hphc_service.exe
O23 - Service: hpqwmiex - Hewlett-Packard Development Company, L.P. - C:\Program Files\Hewlett-Packard\Shared\hpqwmiex.exe
O23 - Service: Intel(R) Matrix Storage Event Monitor (IAANTMON) - Intel Corporation - C:\Program Files\Intel\Intel Matrix Storage Manager\IAANTMon.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: QuickPlay Background Capture Service (QBCS) (QPCapSvc) - Unknown owner - C:\Program Files\HP\QuickPlay\Kernel\TV\QPCapSvc.exe
O23 - Service: QuickPlay Task Scheduler (QTS) (QPSched) - Unknown owner - C:\Program Files\HP\QuickPlay\Kernel\TV\QPSched.exe
O23 - Service: Cyberlink RichVideo Service(CRVS) (RichVideo) - Unknown owner - C:\Program Files\CyberLink\Shared Files\RichVideo.exe
O23 - Service: VundoFix Service (VundoFixSvc) - Atribune.org - C:\Windows\SYSTEM32\VundoFixSVC.exe

--
End of file - 8254 bytes


Gracias por todo una vez más.