Service Startup fails with "Access denied"

Hi,
I've successfully installed Vista Beta 2 Ultimate on my Dell Laptop.
Everything worked fine until I joined our Domain.

Then several services failed to start with "Access denied". This removed
Network access and Windows Audio.

I have changed back to Workgroup mode but the services still fail tostart.
It seems that the Domain-switch modified the local policies but I haven't
found any information what has been changed and how to turn it back (or
better, get it running with the Domain).

Does someone have an idea how to proceed short of reinstalling the whole
thing?

Any help would be greatly appreciated!

Thanks in Advance!

Uwe