My Computer keeps freezing :(

[epcotfan]

For the past week or so my computer keeps freezing and for the life of me I can't figure out why? I've run Norton Utilities, uninstalled some programs, and scanned for viruses. Norton is basically saying my comp is ok yet it keeps locking up. Sometimes online, sometimes off. It was fine about a week ago. I'm hoping it isn't the power source The screen will freeze and I am unable to reboot so I have to turn the darn thing off (which I hate doing)
It is an IBM pentium3 40 gig comp with 128Ram running on Windows ME. I'm wondering if one of Microsoft's latest updates screwed with my system??? The fan seems to be running ok and I opened up the case to gently air dust with compressed air. From the looks of things it was relatively clean inside with the exception some dust on the fan.
I had recently updated Trillian and AIM to the latest versions. I'm wondering if they caused a confict somewhere?

 

[we3luvdisney]

I'm not a computer geek, but I had problems with a virus that Nortons could not repair or fix. I did a search on the web and found some helpful information. They suggested I switch my virus protection, which I did and have not had a problem since. Actually I run both programs.

 

[WebmasterAlex]

Are there any messages at all or is it just a hard lock up? Can you toggle the num lock light on and off with the num lock key?
How soon after you updated the program's did it start happening?
Any other symptom's or warning messages?
BTW compressed air is really not a great thing to use on computers even gently, it forces dust down and into parts. A vaccuum, even a household one is a much better idea as it sucks the dust straight out.