I have a few units of Canon IRC3220 which shows "Waiting to Print" when the customer sends PDF or Word or Excel files sometimes. When I try to cancel the job, the copier will be in 'hang' mode and all the printer jobs will be on hold until the copier is switched off and on again. I have tried installing the PCL5c and PS driver and it is the same. It happens on Windows XP, Windows 7, Mac, Windows Vista. What is the problem?