We use a Savin 2518 copier, wired into our office XP network. Periodically all works well for hours at a time. Then with little notice multiple users send print jobs to the printer before a prior print job is completed and cause the Savin 2518 to "lockup". We then need to shut off printer and restart it. This problem does not occur each time multiple computer send a print job to the printer. We use latest drivers. Any ideas?