Lockups when graphics loaded

[lokii]

Here is the system in question.
Epox ep-8kta2 mb
amd duron 700 mhz
Ati Rage fury 128 32 meg vid card.
WD 4 gig hd.
os's win xp and then win 98se

The problem I am having is this. Whenever I play a game or watch a movie the system locks up in one of 2 ways. The first way happens about 70% of the time. It is a typical lockup where the screen freezes but the mouse pointer is still mobile. This tends to happen if the program being ran is not a full screen program. The second type of lockup takes place mostly when I am doing a game or some other graphics intensive program that is full screen. The system appears to lock up but I am not certain that it is complete. what happens is the monitor acts like it is going into standby mode and powers down. I can still hear audio from the system but alt-tabbing does nothing to affect the problem. I am also not able to shut down the system using keyboard strokes. This may be that the program in question will just not allow use of the windows key but I am unsure.

This system was in working order before using an pci Diamond stealth 16 meg video card and running windows xp. I put the agp ati card in and it worked initially.

First thing I did to try to resolve the issue was to make sure I had the latest drivers for the video card. After that I took the system from win xp back to win 98 se. After that I tried using another video card and MSI nvida geoforce ti 4200. This did not resolve the issue either.

My next train of thought would be the motherboard but I want some input from others before I go to the expense of getting a new one.

One of the most confusing parts of the issue to me is that the programs in question will start up and run for a short time (a min or 2) and then the lock up. I thought it might be a video memory issue but now....

Some of the programs the lockups occur during.
Need for speed hot persuit 2
Harry potter and the Chamber of secrets.
Dark age of Camelot
The Mighty kids meal Yugio cd's.
And many web based programs (javascript shocwave etc)

Any thoughts on this issue would be appreciated.
Thanks

Lokii

[beeboy]

You can try turning down hardware acceleration,and color to 16 bit. You may need more ram. You may need to adjust virtual memory. You might have bad ram. Your PSU may be "underpowered". You may have an over-heating problem. And 700 mh may be a little light for today's games. Yours is a real common problem. You can search posts here for more info.

[lokii]

Another item, I tried using an older game (harry potter and the sorcer stone) that allows either software rendering or D3d hardware rendering. works fine in software but not in hardware.

Lokii

[lokii]

After much hassle and moving around, I changed the memory, power supply, vidoe card, and os initially, I came to determine that the problem was with the agp slot. So I bought a new mb for my main computer and put the one I removed from it into the faulty computer. Not exactly how I wanted to resolve it but....
Thanks for the thought.
Lokii

[beeboy]

I'm glad you found the problem and thanks for getting back to us.