The dv6000 model line is a plague. Google "dv6000" and once the troubles start you know to do one thing. Restore it to the factory load and if that does not clear it up you know to tell them to write it off.

"I don't want to have to wipe the drive and start anew with either Vista or 7 (only as a last resort)."

If it's like the thousand others I've seen that will not fix it.
Bob