When I select Manual Virus Scanning the scanning window pops up and says starting scan with the progress bar scrolling but never starts the actual scan. When I turn on my external drives the scanning windows come up but the progress bar doesn't move and when I click on Cancel nothing happens. I have to log off and log back on to make the windows go away. I am running Norton Antivirus for Macintosh 11.1.1 (2). My OS is 10.5.8. Does anybody have any ideas as to how to fix this?