Client32 out of disk space errors.

I support a 700 user Novell network. I keep experiencing this error message on a hand full of user’s PCs. “Client32 out of disk space while copying Proe080.tmp”. After canceling the error, 3 or 4 different files give the same error message. It onlyhappens at Logon and Logoff. All users and share drives have space. Any ideas on what could be causing the error?