I upgraded my anti-virus software yesterday, getting the latest version of Norton Internet Security. Ever since I installed it (which took about two hours of download-install-reboot-repeat), my computer seems to spend an inordinate amount of time spinning the hard drive even when nothing should be going on. This is highly annoying. I've complained to Symantec and told them that right now I wish I'd never upgraded, but had just renewed my subscription to the virus signature updates for previous versions.
It now takes between 3 and 5 minutes for my computer to boot, and between 1 and 3 minutes to shut down. That is, when it shuts down at all and doesn't have to be force-powered-off.
Sometimes I start thinking the anti-virus software is almost as bad as the viruses it's supposed to be protecting me against.