Hi,
Were there any changes made in the Computer prior to this issue?
Perform the following methods and check:
Method 1: I would recommend you to put the computer in clean boot and then check if the issue persists.
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 to put the computer to start as usual as mentioned in Step 7 in the above KB article.
If the issue doesn’t persists when the Computer is in clean boot or while in the Safe Mode with Networking, then the issue is confirmed to be caused by a certain non-Microsoft applications.
Method 2: Run the fixit from the following link and check:
http://support.microsoft.com/mats/printing_problems/en-us
Also refer:
Printer problems in Windows
http://support.microsoft.com/gp/printing_problems
Let us know if it helps.