It's very important to check on a Linux distribution's web site to see if your hardware is supported! Here is Ubuntu's compatibility list. HP is on the list, but only the server edition.
Each of the better distros has something like Ubuntu's "certified hardware" list or a "check if --- Linux will run on your hardware" page. And you can find a list of the top Linux distributions at http://distrowatch.com and click on one that you find interesting. Their home pages are listed so you can visit them and look for their hardware compatibility pages.
That doesn't have to mean "give up on Ubuntu" though... during the installation process when the partitioner first appears, Ubuntu offers a choice of options. Most beginners let Ubuntu have the whole hard drive (which I guess you did), but if that didn't work, you can (and should, if possible) manually create three partitions:
The first should be twice the size of your machines RAM and should be designated as "Linux swap."
The second should be about 20 GB in size and designated as " / " (ext4), and
The third - the rest of the drive if you want to use Ubuntu as your only OS - can be designated as " /home."
Besure to check the li'l box that says "format this partition" when you're setting them up, and give the partition editor time to "refresh" the list after each one. It may have defaulted to the "do not use this partition" option - and since you designated only one, it halted right there.
Try that - and let us know if it worked! If not, it's a little more trouble but well worth the time to search through those hardware compatibility lists among "newbie friendly" distros.
Hoping this helps,