Hola, antes que nada muchas gracias por responder siempre. Pero no he podido liberarme del maldito about blank y ademas tengo mas troyanos y cada vez que abro un ventana de intenet se abren paginas que yo no quiero, la verdad es que ya no se que hacer, tengo instalado de todo en la maquina y no hay manera de liberarme, borro los archivos con el killbox pero luego vuelven a aparecer. Aqui va de nuevo mi log a ver si puden ayudarme.
Logfile of HijackThis v1.99.1
Scan saved at 09:59:58 p.m., on 03/04/05
Platform: Windows 98 SE (Win9x 4.10.2222A)
MSIE: Internet Explorer v5.00 (5.00.2919.6304)

Running processes:
C:\WINDOWS\SYSTEM\KERNEL32.DLL
C:\WINDOWS\SYSTEM\MSGSRV32.EXE
C:\WINDOWS\SYSTEM\SPOOL32.EXE
C:\WINDOWS\SYSTEM\MPREXE.EXE
C:\WINDOWS\SYSTEM\mmtask.tsk
C:\WINDOWS\SYSTEM\MSTASK.EXE
C:\WINDOWS\SYSTEM\SPOOLSRV32.EXE
C:\WINDOWS\EXPLORER.EXE
C:\WINDOWS\TASKMON.EXE
C:\WINDOWS\SYSTEM\SYSTRAY.EXE
C:\WINDOWS\LOADQM.EXE
C:\PROGRAM FILES\GRISOFT\AVG FREE\AVGCC.EXE
C:\PROGRAM FILES\GRISOFT\AVG FREE\AVGEMC.EXE
C:\PROGRAM FILES\GRISOFT\AVG FREE\AVGAMSVR.EXE
C:\WINDOWS\RUNDLL32.EXE
C:\PROGRAM FILES\MSN MESSENGER\MSNMSGR.EXE
C:\WINDOWS\SYSTEM\WMIEXE.EXE
C:\PROGRAM FILES\INTERNET EXPLORER\IEXPLORE.EXE
C:\PROGRAM FILES\INTERNET EXPLORER\IEXPLORE.EXE
C:\WINDOWS\SYSTEM\DDHELP.EXE
C:\PROGRAM FILES\INTERNET EXPLORER\IEXPLORE.EXE
C:\PROGRAM FILES\HIJACKTHIS\HIJACKTHIS.EXE

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = res://C:\WINDOWS\TEMP\se.dll/sp.html
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = about:blank
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Bar = res://C:\WINDOWS\TEMP\se.dll/sp.html
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = about:blank
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = about:blank
R1 - HKCU\Software\Microsoft\Internet Explorer\Search,SearchAssistant = about:blank
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant = about:blank
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,HomeOldSP = about:blank
O2 - BHO: AcroIEHlprObj Class - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\PROGRAM FILES\ADOBE\ACROBAT 5.0\READER\ACTIVEX\ACROIEHELPER.OCX
O2 - BHO: (no name) - {53707962-6F74-2D53-2644-206D7942484F} - C:\Program Files\Spybot - Search & Destroy\SDHelper.dll
O2 - BHO: (no name) - {2B2FE7BF-A47C-11D9-8DEE-0050AFBA0457} - C:\WINDOWS\SYSTEM\LEMI.DLL (file missing)
O4 - HKLM\..\Run: [ScanRegistry] C:\WINDOWS\scanregw.exe /autorun
O4 - HKLM\..\Run: [TaskMonitor] C:\WINDOWS\taskmon.exe
O4 - HKLM\..\Run: [SystemTray] SysTray.Exe
O4 - HKLM\..\Run: [IrMon] IrMon.exe
O4 - HKLM\..\Run: [LoadPowerProfile] Rundll32.exe powrprof.dll,LoadCurrentPwrScheme
O4 - HKLM\..\Run: [LoadQM] loadqm.exe
O4 - HKLM\..\Run: [AVG7_CC] C:\PROGRA~1\GRISOFT\AVGFRE~1\AVGCC.EXE /STARTUP
O4 - HKLM\..\Run: [AVG7_EMC] C:\PROGRA~1\GRISOFT\AVGFRE~1\AVGEMC.EXE
O4 - HKLM\..\Run: [AVG7_AMSVR] C:\PROGRA~1\GRISOFT\AVGFRE~1\AVGAMSVR.EXE
O4 - HKLM\..\Run: [sre] rundll32.exe sre.dll,Register
O4 - HKLM\..\Run: [NPROTECT] C:\Program Files\Norton Utilities\NPROTECT.EXE
O4 - HKLM\..\Run: [Startup] WinlogonStartup
O4 - HKLM\..\Run: [hbcl] C:\WINDOWS\HBCL.EXE
O4 - HKLM\..\RunServices: [LoadPowerProfile] Rundll32.exe powrprof.dll,LoadCurrentPwrScheme
O4 - HKLM\..\RunServices: [SchedulingAgent] mstask.exe
O4 - HKLM\..\RunServices: [Srv32 spool service] C:\WINDOWS\System\spoolsrv32.exe
O4 - HKLM\..\RunServices: [NPROTECT] C:\Program Files\Norton Utilities\NPROTECT.EXE
O4 - HKLM\..\RunOnce: [ws_uninst] C:\WINDOWS\TEMP\ws_uninst.exe -s
O4 - HKLM\..\RunOnce: [ea_cleanup] C:\WINDOWS\TEMP\EA_CLEANUP.EXE /cleanup
O4 - HKCU\..\Run: [MsnMsgr] "C:\Program Files\MSN Messenger\MsnMsgr.Exe" /background
O4 - Startup: Norton System Doctor.lnk = C:\Program Files\Norton Utilities\SYSDOC32.EXE
O12 - Plugin for .asp: C:\PROGRA~1\INTERN~1\PLUGINS\nppdf32.dll
O18 - Filter: text/html - {2B2FE7BE-A47C-11D9-8DEE-0050C0F6A1CC} - C:\WINDOWS\SYSTEM\LEMI.DLL
O18 - Filter: text/plain - {2B2FE7BE-A47C-11D9-8DEE-0050C0F6A1CC} - C:\WINDOWS\SYSTEM\LEMI.DLL

Como siempre muchisimas gracias.