I have a HP NC6000 and was suffering the same power problems as everyone else. Everyone came to the conclusion that it was a motherboard failure and they were right. Being a broke electronic technician, I found my self in need of a home repair solution because I can not afford the outragouse prices for a new board.
Afer about 2 hours of investigation under a magnifier, I was able to locate two(2) components that were bad. "completely blown off the board". 1 - Capacitor & 1 - Fuse (bothe surface mount. They are (Fuse L1013 & Capcitor C206). For the fuse I just created a solder bridge to create continuity and for the capacitor, I removed one from another different brand board I had laying around).
This worked!, I am sending this post on the NC6000 in question. If you need more info on exactly where the components are located then please post a reply.
Hope I was of some help.