sound starts and stops approximately every 12 seconds. what can I do?
There's a few things that can cause that. If it's a problem with Winamp, switch the output to DirectSound and adjust the sliders to give a larger buffer. (If this is where you are having the problem, come back and say so for detailed help).
If it's happening on every application, try reducing the sound acceleration a bit.
Start>Control Panel>Sounds and Audio devices>Volume (tab)>Speaker Settings>Advanced>Performance.
You'll see "Hardware acceleration" and there is a slider there. Move the slider to the left one notch, click Ok a few times to get out of there and try it again.