Hi,
I would suggest you to refer the link and check.
Method 1:
Step 1:
I would suggest you to check in safe mode.
Start your computer in safe mode
http://windows.microsoft.com/en-US/windows-vista/Start-your-computer-in-safe-mode
Step 2:
If you are able to boot your computer in safe mode, I would suggest you to perform clean boot and check.
Place the computer in a clean boot state and then check if it helps. You can start Windows by using a minimal set of drivers
and startup programs. This kind of startup is known as a "clean boot." A clean boot helps eliminate software conflicts.
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7
http://support.microsoft.com/kb/929135
Note: After troubleshooting, make sure the computer to start as usual as mentioned in Step 7 in the above KB article.
Method 2:
I would also suggest you to refer the link and check.
The "chkdsk /r" command and the "chkdsk /f" command take a long time to run on a Windows Vista-based computer
http://support.microsoft.com/kb/943974
Important: While performing chkdsk on the hard drive if any bad sectors are found on the hard drive when chkdsk tries to
repair that sector if any data available on that might be lost.
Method 3:
I would suggest you to download and install Microsoft safety scanner and run the scan and check.
http://www.microsoft.com/security/scanner/en-us/default.aspx
Note: The Microsoft Safety Scanner expires 10 days after being downloaded. To rerun a scan with the latest anti-malware
definitions, download and run the Microsoft Safety Scanner again.
Note: Any data files
that are infected may only be cleaned by deleting the file entirely, which means there is a potential for data loss.