Optiplex GX620 crashes on ANY sound recording action!!!

I have found out that Optiplex GX620 crashes whenever I try to record audio f.ex. with Windows Audio Recorder. The programs start ok, but at the moment I press Record the machine just crashes!!!

I have updated the BIOS now, and tried the newest audio drivers from Dell. I also changed the audio acceleration slider from the Windows setup to no acceleration with no help.

I am in panic, because I have teaching in two weeks time on those machines and the recording should really work then!

Please, if anyone has any clue to get round this.
Thank you.
Lasse Saari
lasse.saari@campus.jyu.fi
Computer Support
University of Jyväskylä,
Finland