This may help (assuming XP):
1. Restart the spooler service:
Control Panel -->Admin Tools -->Services-->Print spooler-->Stop and start
2. Delete the actual files telling the spooler it has something to print:
C drive --> Windows--> System32 --> spool--> PRINTERS --> There will be 2 files for every document that is in the queue. Delete them and restart your computer.
Also
How to cancel printing or to delete a print job that is stuck in the print queue in Windows XP
Search for "problem deleting print job" in MS site.
SD