Two things to try:
1. In task manager see if any (other) process is using way too much CPU. Could be malware or some other issue.
2. Try the old PIO-DMA trick from http://winhlp.com/node/10. It won't harm after setting it to PIO and setting it to DMA again.
I have a Gateway GX7022E desktop with Windows XP Professional OS that my wife uses. I have several simple games on it as well as some music. The problem that has started is any audio or video that plays on it skips or stutters. This includes CD's as well. I have tried to go to Microsoft and use the programs that they offer to find the problem with no success as well as the trouble shooting software on the computer. Anyone out there have any idea as to what has happened to this computer or a possible solution to it.