computer freezes after 12hrs

I have already done all the steps for removing malware and my logs are clean and it was recommended that I ask for help here with software. So here's the problem.
About every 12 hrs, my computer, whether I am online running MSN or not, stops responding. It won't do any requested task and gives me an error message about there not being enough resources. After I reboot --by hitting the'reset' button-- it is fine for another 12 hrs.
I haven't added any new hardware.
And I can't pinpoint the beginning of this to correspond with any particular program I added---- I do download and try stuff alot. I've been trying to figure this out for 3 months----didn't know this site existed
I'm running XP Pro with all the servicepacs and updates. I've got the student version of Office
I've got an AMD 2100 processor, a WD 80 Gig HD, 512 DDR SDRAM and use DSL
I use Avast, ADaware, Spybot, ZoneAlarm, Registry First Aid
I use MSN for browsing and my email and have for years---It recently started giving me alot of runtime errors so I called MSN and reinstalled it---still get some errors.
I don't know if it's related to the freezing or not.
I've tried turning off my screensaver---doesn't help
I took the side off the box and cleaned it with a can of air and while Motherboard Monitor says it is running alot cooler ( it was not running hot---but it is cooler) it still quits responding ---it won't even shutdown then except with the 'reset' button---about every 12 hrs
Thanks

 

Get Everest avalable here http://majorgeeks.com/download.php?det=4181 and check out your Voltages, because it really sound like your PSU is cr*pping out. The good side is it's cheap and easy to replace

Oh yea and welcome to Major Geeks

 

Thank you.
I downloaded it and ran it but I don't have any idea how to understand what I'm looking for. I read the instructions but I don't still don't get it. Help

 

Okay click on Everest/computer/sensors and this will give you your temps/fan speed/voltages your voltages should be know more than 0.25 less/more than stated EG +5Volts - 4.65Volts a problem........+5volts - 4.95Volts all okay.

Just remember that even if the voltages are okay you can still have a fault PSU, all OEM's put in the cheapest PSU's they can, this is were they can save money. Hope that helps

 

OK I did that and right now they are within range but I will try to check closer to the 12hr mark. I built this machine myself about 3 years ago and I remember I didn't put a very large PSU in it ---maybe 350 at the most (not being aware of the advantage of a bigger one and trying to save money just like the manufacturers Also my APC software has been telling me that the battery in it is old and I should replace it. Any of those things a possibility?

 

I'd be looking at a slow heat buildup. Fans full of gunk maybe??
HTH
Robert

 

Robert
that was one of the things I considered but as I run motherboard moniter it didn't show up that it was. Just in case acouple of weeks ago I did take a can of air and clean out the whole case. It runs cooler than it did but still no slow climb in tempurature
Thanks