Hi Tom,
Welcome to Microsoft community and sorry for the delay in replying.
Since when are you facing this issue? Did you make any recent software or hardware changes on the computer?
This could be happening if any of the background programs is conflicting with the application. To help troubleshoot error messages and other issues, you can start Windows 7 by using a minimal set of drivers and startup programs. This kind of startup is known as a "clean boot." A clean boot helps eliminate software conflicts.
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 How to reset the computer to start normally after clean boot troubleshooting
Hope it helps and do let us know if you need further assistance. We will be glad to help.