Computer crashes, I need ideas on cause

What exactly does it do? BSOD, just shut off, or error message?
Please explain.

The fact that it only happens on myspace says that your computer has an issue with your page on myspace. If you got pic's and flashy things to put on your page, they might have contained a virus. But a virus would likely be caught by your protection software. It might be some other software issue. But since you have a fairly new computer, I suggest doing a simple revert of your whole system. I have XP media center edition, and it's easy to do. I'm pretty sure home edition can as well. But if it only happens on your page, not others. Cancel your account and start a new one as well as the revert.

If you installed any new software, you will need to re-install the software. But you can also use MS support. They will guide you through the process over the phone on how to share your computer and they can check it out.

If you don't like those ideas, there is plenty of freeware that runs diagnostics on your PC that XP doesn't do. I'm assuming you've done that. But the freeware is discussed on many of the other computer help forums from last month. I am sorry I don't have the links, but they're not hard to find.

Good luck to you

"Processor: Intel(R) Pentium(R) 4 CPU 2.40GHz (2 CPUs)
Memory: 2558MB RAM"

Armed with only this I'm going to take a wild guess you have a pair of 1GB sticks and 2 256MB sticks.

-> Remove the 2 pair of 256MB sticks and retest.

The second clue is the 2.4GHz (2 CPUs). That could be the old 2.4GHz HT chip. At that age I'd refresh the heatsink compound, clean the heatsink and if that fan isn't working as it did when new then replace the fan.

I'd leave the case cover off during tests.

Bob