Boot the computer in clean boot and check which third party application is causing the problem. Follow the steps from this article 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 you have finished troubleshooting, follow step 7 to boot the computer in normal startup.
Perform a chkdsk /r to check windows files for corruption.
a. Go to Start and type cmd.
b. Right click on cmd and select “Run as Administrator”.
c. Type CHKDSK /R and press Enter.
d. You will be asked if you want to schedule this volume to be checked the next time the system restarts: Press Y and press the Enter key.
NOTE: Do not restart the computer while check disc is running.
e. The system may or may not ask you for your windows CD. If it does, insert the CD
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. Please backup data before performing this on your computer.
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