I have an iMac running mac os x 10.4.11. Recently I ran a scan with Norton. It got stuck on one file and wouldn't complete the scan. I tried it 2 more times. Each time I got a black screen and had to manually restart. About the same time I started getting a grey screen that would roll down from top to bottom with a message that said I had to restart because os x had quit unexpectedly. When this happens I have apple mail open. Can you help?