Strange. I suppose that you do have a sound card in the computer?
What happened to me, about two years ago, when moving this computer from one room to another, was that the sound card fell out of its slot in the motherboard because the OEM had not fitted a retaining screw to hold the card firmly in place.
I would disconnect from the power supply and unplug your modem and printer, etc. take of the left-side panel and lay the computer (if a tower) on its right side on a carpeted floor. Then see if the sound card is properly in its slot in the motherboard.
Take it out and put it back in again in any case and make sure that there is a retaining screw fitted.
You could re-seat the RAM module(s) whilst you are in there and if you have less than 1024Mb of RAM you might want to use the opportunity to check your RAM modules serial numbers and possibly order some more.
XP can use up to 4 x 1024Mb of RAM and if you run dxdiag and can see that there is a paging file, when all of your programs are running then you need more RAM anyway.
More RAM = less paging file, and as RAM is faster than using the paging file your entire system will become faster and more responsive and less likely to hang or freeze up.
Just make sure that you take proper anti-static precautions, don't wer static producig clothing and hold the bare metal with your left hand whilst pressing in the start-button with your right hand to equalise and standing static voltage acrosss the circuitry before touching anything inside.
You can use an anti-static wrist-strap and crocodile clip too but they are rather tedious to use.
