I have a very strange situation where the CPU on our print server runs at 100% for most of the night. During the day it backs down to normal levels. It started when we installed new printers. It is the spooler service that is causing it, at least according to the logs. I have removed all old drivers and installed the latest ones for the new printers. I have started a scheduled job to kill the process and restart it again each night. This temporarily brings the CPU back again but with in 1/2 to 1 hr it's back up again. Nothing shows up on AV software scans although it does feel like some malware is at work but I cannot track it down.