HP Pavilion DM4 - No sound through speakers/headphones but USB works

Hi All,

Have a user with a HP Pavilion DM4, and the sound refuses to work.

All sound-related services are running fine, there is no red cross on the system tray icon, and no errors in the event log or Device Manager. Essentially, everything appears to work correctly.

However, no sound comes out of the laptop speakers, nor does it come out of a headset when plugged into the line in jack on the side of the laptop.

Now, here's the weird bit... If I plug a USB headset in, sound works absolutely FINE!

I've tried uninstalling the IDT HD sound device drivers, and reinstalling a different version, as suggested in some threads I saw, but no dice.

Anyone had anything similar?

Thanks in advance

Dave