Hi,
1. Since when are you facing this issue?
2. Did you make any recent changes?
I would suggest you to follow these steps and check if it helps.
Method 1:
Try booting the computer in safe mode and check if the same issue occurs, here is the link:
http://windows.microsoft.com/en-US/windows7/Start-your-computer-in-safe-mode
Method 2:
Try performing clean boot and check if it helps, here is the link:
http://support.microsoft.com/kb/929135
NOTE: After you have finished troubleshooting, make sure you put back the computer to normal startup mode as suggested in step7 from the above KB article.
Azam – Microsoft Support.
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