Hi!
Has this PC been "made" for you by a friend or have you put it together
yourself, or is it from a shop. The only reason I ask is because what you
are describing is what happens when a power supply can't cope. The 3000XP
takes a fair amount of power, so anything other than around 350watts is
not going to power the PC properly when you think about the fancy stuff
you have plugged in.
If the power supply can't cope, usually you start noticing screechy or
non-existant sound, or broken/distorted sound after a few minutes or when
you move the mouse. The video display can be the same, distorted and
going off after a while.
What you need to do is look at the wattage of the power supply, i would
suggest someting above 300w, maybe nearer to the 500w mark.
www.aria.co.uk were selling some cheap 550w power supplies a while back.
Often it's cheaper to buy a case with a power supply included.
I found the above problems using an ASROCK motherboard and Athlon 3000XP.
i had installed everything into a case that had only a 200w power supply
and thought at first it was the board, then the sound, then the video side
of things. All mine were built in to the main board. The case and power
supply had happily run the Athlon 750 for years, so it was only when I
looked at the specifications I realised it was the power supply.
I had contacted ASROCK and spoken to people on newsgroups ad the usual
"EXPERT" advice was - install the latest drivers, don't plug the mouse
into the USB port, shut windows down and start it up again. Loads of the
usual rubbish !
So before spending loads, check your power supply and see if you can
borrow a better one. You will also need to go into the BIOS by holding
down DEL, F1 or F2, whichever it is on your board. Check you have the
devices switched on. The fact you said you HAD sound at one point makes
me think you have the drivers installed, so no need to check all that
again - unless you have done something to it.
Good luck!