Issue
Microsoft have identified an issue when "LPR Byte Counting Enabled" is checked in the Windows Standard TCP/IP port which can cause slow printing, or even behaviour which causes a print job to spool over and over again (possibly causing print ).
Resolution
To resolve the issue simply un-check the "LPR Byte Counting Enabled" option in the TCP/IP port properties.
For more information on the issue please refer to the following Microsoft knowledge base article:
http://support.microsoft.com/kb/816627
http://support.microsoft.com/kb/970048