And tell what PC this is, the OS and if system restore to when it worked is possible.
There is malware beyond other causes such ENHANCED CLIPBOARDS (see Yankee Clipper) so let's take Grif's advice too -> http://forums.cnet.com/7726-19411_102-5070551.html?tag=posts;msg5070551
Bob
Every time I try to cut and paste, my computer freezes up. The only way I can close out is to reboot, which I know is bad for my computer. I never realized how often I copy things until this happened. I must have rebooted a hundred times by now. It is impossible for me to pick up the computer and take it to a repairman and expensive for them to come to me. I would appreciate any suggestions.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic