Documents stuck in print spooler

Hi folks,

I have a Lexmark X6170 all-in-one connected to Vista Ultimate 32 PC and shared. When I print from my second machine (XP) the document prints OK, but sometimes it stuck in the spooler, prints itself again each time I power up the printer and prevents other documents from being printed. When trying to cancel it nothing happens - it stays in the spooler and doesn't go until I turn off the spooler service and delete the files from the spool folder. Any ideas?

TIA