Programs shutdown after aprox. 5-10 minutes...

Exactly as the title says..... programs shut down in around 5-10 minutes...
its especially annoying when playing games... like starcraft, i usually play on lan with my brother, but after reinstalling windows xp, it usually shuts itself after 5 minutes.... and same happens with diablo II, but not programs like IE and Winamp... is there a solution to this problem?

System Specs:
Windows Xp Pro
Intel Pentium III
909MHz
512MB RAM
Intel 82815 graphics controller
1.5mbps internet speed
2 HD that have 10 GB each and 1 HD with 20 GB

 

It might be an overheating problem, but it doesn't seem like it. Do you have the latest drivers for you graphics? Did it just start after installing XP? And what OS did you have before this started to happen?

 

IF it really is a complete Shutdown, then the cause is either PSU (or related settings being incorrect in OS and/or BIOS) or overheating (mainly CPU or Video Card GPU).
You gave the biggest clue...when playing games (one of the most graphic driven processes you can run that is also a heavy use on Video Card) hence the possible overheating of the GPU on the video card.
Make sure all your fans are in working condition...PSU fan in the back of the case, the fan located on the heatsink connected to the CPU, also the one on the Video Card(if there is one).
Depending on the case and the devices and the overall heat produced within the case (even if all the applicable fans are working) there may not be adequate cooling/air circulation in the case which as a result would cause the vital components like CPU and Video Card to overheat...this would be even more applicable to the Video Card if it only has a heatsink but no fan because the heatsink alone without proper air circulation would not mean much.
Reboots could be overheating, PSU and also RAM.
System Freezing would be mostly RAM, corrupt OS or HardDrive.

...I hate to say it but the last 2 also be caused by some sort of a malware infection as well.

 

Make sure you blow that puppy clean, too. Buildup of dirt and dust can cause overheating as well.

 

umm i was using windows XP before i reinstalled it, i reinstalled it because of another previous problem, which i solved in this forum

and.... i also havent used the computer in like 8 months, so yeah theres tons of dust. I'm going to get a dust blower and clean the fans (they all work)

the fans work alot, creating tons of noise, and the video card is usually warm, which i just installed yesterday to see if that would fix the problem. but both internal and external graphics made the game shutdown so..., i dont know if that would fix the problem....

edit: also about the air circulation, i dont know what to do about that, because i dont know about hardware stuff that much, so... would leaving the case, which opens on the side, open be any help to the circulation?
and btw the new graphic card i installed is GeForce FX 5200.

 

hmmmm... just to give more info, when i first had the computer, it never shut down for no reason ever before.... so after i dust it and nothing gets better, do i have to get things to improve it? and what should i buy to fix it?
plus the new graphic card has its own fan, but i dont really know what a heat sink is, is it the metal bars that stick out of the card and makes a circle?