Xp clipboard problem

My clipboard keeps filling up with screenshots of the desktop. I can't use the cut and paste because whatever I cut, gets overwritten by a new screenshot every 2 seconds. I have done a full scan for malware and viruses. This is really annoying. When I view the clipboard using clipbrd.exe it shows the new screen shots coming up in new windows about every 2 or 3 seconds. Any ideas what is causing this?