Just a thought. Normally Norton tries to do a full virus scan when it notices the CPU is idle. Like overnight if you leave the comouter running. If it isn't able to do one for a long time it will force a scan maybe when you're busy doing something else. The only way I've found to stop the scan is to shut down the computer. It won't close from Task Manager and I've never found a suspend or stop option in Norton. Good luck.