Wow, I am pretty sure the problem is not Ubuntu and might be something worse. I had an HP DV6000 (Sold the laptop about a month back) and that puppy was running fine with 12.10.
The problem I encountered with that laptop (Just in case I had the one with the Intel video card) is that, since it was pretty old by now, the same issue you mentioned happened to me but on Ubuntu 11.10, at the end it was not Ubuntu but the cables that connect from the Power button to the Quick buttons and the hard drive.
It is basically a ribbon that connects that, that somehow fails "sometimes" and "sometimes" doesn't. If you happen to hold pressure on top of the left part of the keyboard or nearby or above the touchpad and suddenly it does not work or it does work and does not fail, then it is the ribbon.
This is the quickest one I found: http://www.ebay.com/itm/HP-DV6000-DV9000-KOTL-E220709-AWM-20798-80C-60V-RIBBON-SWITCH-CABLE-POWER-BUTTON-/400313605577?pt=LH_DefaultDomain_0&hash=item5d348cddc9 (Was looking in Amazon but that place sucks in having a better advanced filter). To change it there are steps to do that and is not hard. Will take you if it is the first time you work on the laptop between 15 to 20 minutes.
I would suggest to actually remove the 2 ribbons it has right now and change both for the new ones.
The battery is another problem since the original one will start failing (At least failing to charge) after 2-3 years. I bought a newer, bigger one before selling it. but when I sold the laptop I included the older one but warned the buyer that it would only last about 10 to 15 "Real" minutes. I say real since Windows or Ubuntu will say an hour.
I am sorry to give you such bad news about this, at least you have the solution which I had to live with for about 5 months until giving up and trying to solve the problem myself (In my country it is tough to find a way to fix this laptop and they were charging me about 200$ for something that actually costs 50$ including labor). For you it will cost less than 10$ since with that you can buy the 2 cables. I even saw one guy selling 4 of them for 10$.
Hope you solve the problem with this since I know how it feels. That laptop is the best one I have had so far.