Memory leak in spoolsv.exe if you use HP standard TCP/IP port for printers. Non-paged memory pool keeps growing when you print. Solution is to change HP standard TCP/IP port to Microsoft Standard TCP/IP port
Solution was found here: http://www.tek-tips.com/viewthread.cfm?qid=1143952&page=1
Case was escalated to HP who confirmed that they recommend to change to Microsoft port driver.