I have win2k pro and I'm running IE5.5, SP1. win2k has been running great for 5-6 months, except...

Several times I've had EVERYTHING freeze up on me. This only happens when IE is running. When I say it freezes I mean everything, no ctrl-alt-del will work, nothing. I've got to power down and reboot. I know this kind of shutdown can't be good on an "NT" machine, so I really need to get this one fixed.