Losing Paste option

I have a Win98 PC that loses the paste option. It looks like it copies (nothing shows up in the clipboard) and then when you go to paste the option grays out. I can get it back with a log off and login as diferent user. (Novell, Client 3.3 sp3). The end user says it only lasts about 2 hours. He uses the keyboard shortcuts to copy and paste. He also uses it alot in Netscape.
Have installed IE, no help, fdisk, formated and reimaged, no help. Would appreciate an ideas, been working on this for 1 month!