disc space is full error

In one of the high schools i work for, some students are getting this error message when trying to save to the "a" drive and to the server - "disc space is full" now I know the server has lots of space and the floppies are blank. the machines are about a year old, celeron 400-433 with WinNT workstation. It only happens on certain machines and does not follow the students with their profiles. Any ideas? Could it be with the policy editor? Any help would be welcome. Thanks!
Coops