I've been working on this problem for quite awhile now and I can't seem to get it nailed down.
The problem is that XP will be running fine and everything is going okay until randomly everything will begin to lock up. The mouse stays responsive for awhile and I am still able to interact with certain windows for awhile until everything completely freezes about 20 seconds later and the motherboard speaker goes off with a continuous tone.
It would appear that ever since I reset my BIOS to defaults and updated them that the crash happens less frequently. Until today while watching Lost on my computer it seems to do the same type of crashing during the middle of videos. I timed it twice and both times it happened exactly 45 minutes after post screen, very strange. I was having some codec issues prior but I believe them to be worked out.
I have run MANY hardware checks and am convinced it is not the hardware. I have also run check disk multiple times and done several virus scans and two windows repair installs.
I have run MemTest, Prime 95, Burn-in Test, pretty much everything I know of and all have come back clean.
It's not overheating, I have always been watching the temps with speedfan.
I also noticed when I managed to bring up the task manager during a crash that 0% of the CPU was being used, even by System Idle Process.
Quite frankly I am out of ideas. I'd like to be able to fix this without reformatting. Any recommendations?
Also, I noticed this morning that when I left the computer on last night it crashed about an hour after me going to bed and when I came back it's the same old story with the mouse being responsive for 15 seconds and then the motherboard speaker going off.
Sorry, that was a late night mumbling more than a decent answer.
Your Rosewill PSU is a very poor unit that could well have out of spec V-droop or ripple, especially in a warmer environment.
That would be my immediate suspect, but it's by no means certain.
Did you mention your motherboard anywhere? I don't see it. You also don't say if this is a new build, or the problem just started.
Even though you aren't technically overheating, some part somewhere is getting to warm to operate properly. Because the behaviors you describe are a bit bizarre, that's an argument for a power problem.