Computer Keeps Freezing?

I have an older Gateway 700XL (1gb ram,ati radeon 7500,160gb hdd,3ghz p4 HT) it does have a dedicated sound card but off hand I don't remember what it is. Anyways occasionally during video playback or dvd burning the computer freezes hard with a loud skipping scratchy noise coming from the speakers. Nothing I do will break the freeze except for holding the power button and rebooting. Lately the frequency of this issue has been increased. I have tried to find driver updates but there doesnt seem to be any support anymore for this model What could it be and What can I do?