Sound, only sometimes though

i have a major problem with my ibook. when i wake the book, or after i start it the sound works. after not having the any sound on for a couple minutes, when i try to play a sound, usually a song, no sound comes out. what can i do about this?

Has this just happened today? Is problem on a regular basis? If it just happened, you should just restart the computer and see if the problem comes about again.

it happened today but i have tried to restart the computer. i have also tried shutting all programs down and then bringing them back up.

I guess, you'll need to try the all mighty verify/repair permissions thingy. And it wouldn't hurt to restart after that also.