http://www.computing.net/answers/hardwa ... 59238.html
As stated, run check disk, and then your HDD manufactures drive check. To do this you will require a copy of your installation CD for your system. If you don't have one then request one from HP, as the next step requires you to do a repair installation, which isn't noted as a reply.
Could start with a HDD check with the tools provided on the UBCD disc for your HDD. Then go from there.
Visit the UBCD Wiki: http://wiki.ultimatebootcd.com
Please check your UBCD
ISO MD5 Hash Sum
; May prevent issues later on by not having an exact copy.
Currently Working on Common Issues and Repair Tips
on the Wiki.