Wave sound just turns off!?!
First step is to check the manufacturer for updated drivers.
If you have Cmedia onboard sound, you may have a 'problem' that I had
for awhile--I had some "hot keys" programmed to raise and lower the
volume with <ctl>-<up>, etc. I found that I would inadvertantly turn
the sound down while doing normal things, like playing a game or
typing, and the sound would disappear. Other sound cards may also
have such settings, whcih you can usually set in their mixer program.
You may just have volume or mute set to a hot key.