There have been reports of this happening with a screenshot program called Jing. Try disabling Jing (or uninstall it) to see if that allows you to use the program.
To disable Jing:
- Click on Start > All Programs > Accessories > Run (or Start > Run in Windows XP).
- Type in "msconfig" (without quotes) and click OK.
- Once the System Configuration Utility comes up, click on the Startup tab.
- Find the Jing program on the list and uncheck it.
- Click OK.
- Restart the computer as prompted.
It is possible that a different program on the Startup tab list is causing the program. If so, try disabling half of the programs there and restart. If the problem goes away, you know it's one of the ones you disabled.
Continue with that process until you narrow down which program is causing the conflict.