The service is ticked on msconfig.
this enable/re-enable thing I didnt tried, just checked it now, but no success.
I have only one more idea: Reinstall windows Vista and check if sound works again.
But I will not lose time with that anymore, I will do what frankstr2196 did.. buy a Creative 5.1+ PCI card, at least my Inspiron 5.1 will work better than this 2.1 onboard.
Thanks for your help!