Hi experts

I'm new to Linux and I'm having a sound problem.

Laptop: HP DV7/Intel/Nvidia. The newest Ubuntu (9.04 I think)

I can see others have problems with the sound too, but it seems I have a different problem.

On the Login screen I kind of have sound. It sounds like bongo drums beeing hit rapidly, This works both on the internal speakers and on the headphone jack.

BUT, as I said, it doesn't sound right and after login, I have NO sound.

Anybody that can help me?