HP Laserjet Freezing

I have a HP Laserjet 4000 installed on my network that suddenly started freezing on an intermittant basis for a few weeks now. When you try to print to the printer the job just sits in the que and doesn’t print – No error messages come up on the printer or the print server (NT server) but if you turn the printer off and then turn it back on the print job will come out. there are no other jobs stuck in the que and the problem only happens once or twice per day. Any ideas?????