Audio repressed in Windows XP?

I have a NEC Laptop with an Intel video card and a Pentium IV with 1.4 GHz. It runs Windows XP. Now I want to bring up an issue that I’ve been wondering about for quite some time.

Sometimes, completely without explanation, the sound quits. Now I’ve tried a dozen things, but one thing I did notice was that when I shut down that Laptop, at the end of closing down apps, it suddenly manages to play the Windows Exit music theme. So my question is, are there any programs/processes that can cause audio to be repressed?

Should not. Try looking at and perhaps find the latest audio drivers for the laptop on the NEC site. (actually look for any and all updates) If it becomes a real problem reload the thing. It must have come with a OEM reload disc.