Weird problem with my HP 8510p laptop

So I have an HP 8510p 2GB RAM, 80GB HDD, ATI Video card and winXP SP2 installed. The weird problem I'm having is that the laptop for some odd reason crashes while its booting up. I have replaced the HDD and still acts the same way. For some reason it does not read the hard drive. I have taken the laptop apart and checked the SATA connection between the motherboard and the connector and it seems to be connected (I used a DMM and checked for connectivity pin by pin). Later on I found out that by flushing or resetting the BIOS chip by removing the BIOS battery, the laptop will boot fine. However if I reset the laptop and try to boot again for a second time it will start crashing during boot up (showing the blue screen of death and the shutting itself down). In order for me to boot back into windows xp, I have to flush or reset the BIOS chip by again removing all power from the laptop and the BIOS battery. But again, if I try to reset my computer, it starts crashing during boot up.
What is going on with my laptop? Any ideas? Could it be a BIOS problem? I ran the BIOS HDD Self Test and it passes. I have reset the BIOS setting and still having the same problem. Even when I try to reinstall XP, for some reason the hard drive can't be seen in the installation. I know its not the hard drive or the installation of XP. I have connected all of my laptop hard drives on other laptops and they work fine. Something is going on in the motherboard and/or the BIOS chip. Has anyone ever experienced something like this?

Thanks in advance.
Andy