Hi,
1. What is the make and model of the computer?
2. Which security software is installed?
3. Which update was installed recently?
Method 1.
As this issue occurred after a recent update, you may try a system restore and check if this helps.
You can use the restore points to return Windows 7 to a previous state when your computer was functioning correctly.
System Restore:
http://windows.microsoft.com/en-us/windows7/products/features/system-restore
Important: System Restore will not revert any of the non-system files like documents, email, music, etc. to a previous state. These types files are completely unaffected by System Restore. If your intention
with this tool was to recover a deleted non-system file, try using a file recovery program instead of System Restore.
Method 2.
As the issue does not occur in a new user account, you may refer to this article and check if this helps.
Fix a corrupted user profile:
http://windows.microsoft.com/en-us/windows7/fix-a-corrupted-user-profile
Method 3.
Run a full computer scan with the Microsoft Safety Scanner to make sure that the computer is virus free.
Microsoft Safety Scanner:
http://www.microsoft.com/security/scanner/en-us/default.aspx
Safety Scanner Disclaimer: There could be a loss of data while performing a scan using Microsoft safety scanner to eliminate virus if any.
Let us know if you need further help with any windows issue. We will be glad to help.