Bus hang up when playing games question.

My Micron Athlon 1.2 G and 256MBRAM with a GFX 2 GTS video card initially starts working fine in all games, but in many games, such as NWN and Morrowwind, after about an hour of game play, the bus periodicly will hang for a second or two. The game keeps running, because the graphics will leap ahead when the game returns. But the controls will lock up every ten or twenty seconds. The refresh rate for the monitor seems not even to flicker (keeps on working great) but the sound will skip and replay. I looked for conflicts but found none.

Does anyone know what could cause this?

Thanks.