I was having the most insane, inexplicable problems, including the Windows encountering a problem, , constant shutting down, getting kicked off the net, etc. I was on a thread complaining about it all and two people far more knowlegable than me pointed to ZoneAlarm as a problematic installation. I finally uninstalled it and have not had any problems since (fingers crossed).
I'm had Zone Alarm for years and never a problem. I'm back on IE 6 now by the way and it's acting normal again - go figure.