Windows 7 log on log off loop

[GaMeR-BoY]

I have a computer with Windows 7 Home Premium. Something went wrong yesterday and then it refused to start. It would hung at a black screen and wont reach Windows 7 logon screen. I don't know what was wrong and so i tried to start Windows 7 in safe mode. It started perfectly. Now i ran a full system scan and after 4 hours there were three virus infection which the antivirus needed reboot to clean them, I rebooted and then started in normal mode and it started. I logged into my account and before the logon sound completed, i got logged off and the log off sound played. I cannot logon now. I tried the second user but failed with it too. What can be done in such case? Please help...

[Noverism]

I think you should have a look at these links :
windows xp log on/log off loop
Windows XP logon/logoff loop
need help with windows/ log in log off loop
Windows Boot Loop
Windows XP Repair stuck in loop
These may help you...

[Solomon]

Boot your computer with Windows 7 DVD and then select repair install. Let Windows 7 repair the existing operating system and wait to see what happens. I think the virus infection is causing the log on and log off loop. This is cause due to a virus which infected many computers with Windows XP. I did not knew this could affect Windows 7 too. After the Windows 7 repair finishes, update your antivirus and again run a full system scan. If there are still viruses on your computer let the antivirus heal them. This should help.

[Devasis]

I think before repairing the Windows 7 installation you should try to repair it from recovery console as it is less time consuming. Boot with Windows 7 install DVD or recovery disk, Select repair and then select command prompt. Once you are at C:\Windows> type : "cd system32" without quotes and press Enter. Now type "dir userinit.exe" without quotes and type enter. Now type this command : "copy C:\Windows\ServicePackFiles\i386\userinit.exe" If this command fails then you need to copy this file from DVD. Suppose your DVD Rom's drive letter is "Z" accordingly type this command : "copy Z:\Windows\ServicePackFiles\i386\userinit.ex_ userinit.exe" Then again type : "copy userinit.exe wsaupdater.exe" Now you should be able to boot into windows. Hope this helps...