Citrix/Win2K server print problems

i have a citrix xp terminal server on a win2k network. citrix auto-creates printers for local workstations. during busier periods of the day the workstations will be unable to print, even if they have printed countless times prior. Their session will “freeze” and when they do a restart the printer will not work. To correct the situation I have to restart the spooler. My question is why is this “freeze” occuring and how do I fix it? It only happens when they begin a print job.