Bizarre T40 sound problem

[jargoone]

I have a T40 that has problems with its sound card. System beeps in BIOS work, sound card is detected, but no sound in Windows.

When messing with the system, I turned the volume up all the way. I was reassembling with it powered on, and I realized I was hearing something strange. Depending on what I did, I could hear feedback. It is as if there's a microphone plugged in, and the output is sent out the speakers. I could tap, snap my fingers near the microphone port and hear it out the front.

What the heck is going on here?

[agarza]

Make sure you have Wave enabled, or follow this graphic:
http://img509.imageshack.us/img509/515/wavetr1.png

since when this behavior?