Backdoor for CMOS password

Most HP computers have a CMOS battery... a round battery a little bigger than a nickel but smaller than a quarter (Usually it is a 2032 battery on the main system board). Remove the battery, wait a minute or so, then replace it. That will erase everything in CMOS. You will need to re-input date/time, re-decect your hard disk drive, etc.

http://www.heise.de/ct/english/98/08/194/
http://www.tweakfiles.com/bios/bios.html

The best thing is to go to HP service and ask them to reset CMOS, it may cost you a few dollars only.
If you want to play - you can clear CMOS by shorting pins. To find them, you must look on the board for something as JBAT, Clear Data/Keep Data, CMOS RAM, etc. When you located them - short them, while the system is off.
Removing a battery may help in resetting same data but it's usually for date and time only.

Anna is right, there are up to 3 batteries in a laptop. The main power, the cmos and sometimes a "resume".
First, there is always a back door. You will have to contact HP and prove that you have ownership rights to the laptop. If that is not the case then you have no other option but to open the laptop. Although the suggestion about the bios tweak is a good idea it will not work as it relies on a booting computer to access the exe program. As the bios has been told to get a password before itpasses over to the bootstrap, any program software will not work. (there is always hypnotism, for you not the laptop!)There is no other solution but to remove the cmos power and then short the circuit. Make sure you have removed all of the batteriesbefore doing this. Make sure you and the laptop have been grounded as well. It is not that hard to open a laptop, I do it every day. The trick is to use your fingernails as prying tools and then a thin flexible blade or 2 to work the pressure points. A dull (old) paring knife works great. The thing to remember is if you think it is too much pressure, stop and try another spot. Make a map of the computer and the location of the screws that you removed, (length as well)
If this sound too much, phone HP for a service centre in your area. They have a great 1-800 help line.
p.s. you are lucky it is not an IBM, then you would have no choice but to look for proof of ownership as only IBM can remove it.
Good luck Chris

Don't be afraid of open your laptop, it's easy.
1.- Find the correct screw driver!.
2.- Remove your battery pack. Touch any big metal surface at home to discharge static.
3.- Remove screws and remove cover. Take it easy, watch for screws in hidden places. Most pc's has a sign like => pointing to the screw that has to be removed.
4.- Carefully remove cover. It is allways connected with the rest of the computer with a flat cable or a connector.
5.- Search for a battery pack like the ones that have home-phones, clocks. It should not be difficult to find, they are allways in esay access places. (you are not the only one that forgot passwords!!)
6.-Remove It's cable connectors and leave it open for 3 to 5 minutes.
Reasemmble all again. Be carefull, avoid touching integrated ciruit pin's.
7.- Start laptop again and follow bios setup
again.
Good luck