Method 1:
Start the computer in Safe mode and check if you have the same issue appearing.
Start your computer in safe mode
http://windows.microsoft.com/en-US/windows7/Start-your-computer-in-safe-mode
If computer works fine in safe mode, then follow the Method 2 and check.
Method 2:
Perform clean boot and check.
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 these steps to reset the computer to start as usual. Refer step 7 in the article.
Method 3:
.Net Framework Repair.
1. Go to Control panel.
2. Choose Uninstall a program under Programs and Features.
3. Click on .net framework 4.0 client profile and then click on Repair.
4. Wait till the Repair process completes and restart the computer.
Method 4:
Run a malware scan and check if there are any threats.
http://www.microsoft.com/security/scanner/en-us/default.aspx
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.
Hope it helps.
