will not recognize internal hard drive

I have a strange problem with a 2009 MacBookPro. It started acting "strange" for the user over the past few months. By "strange" I mean it would freeze, or fail to boot, or sometimes even restart without any reason. Now, it gets even stranger. Tried the standard things, RAM reseat, replace, check for loose connectors etc. It would fail to boot when the hard drive was connected internally. Then it would give a kernal panic and fail to even recognize a hard drive as being installed. Did a PRam reset, SMC reset and even the power off/control key to try to reset the open firmware. No sucess with anything. This is a suystem with an internal battery.

Yet, when using this exact same hard drive on an external USB drive connection, it would boot fine. Next tried it in Terminal mode to boot up another MBP. Failed to boot. When the 2nd MBP was booted from its internal drive and the suspect machine was plugged in as a Firewire (Terminal mode on "strange" computer) an External Firewire Drive appeared on the desktop, then a few seconds later, an identical copy of the first Ext FW drive appeared. This went on with evenbtually six copies of the one single Terminal booted hard drive appearing on the desktop of the second computer. None of the six drives would open or even allow any indiccation of what they contained.

Tried to partition the hard drive when it was put back into the internal slot but it would not unmount and failed to partition. The same thinmg happened when trying to erase it. Connected the hard drive via USB to a Windows 7 machine and used it to erase both the Recovery and Main partitions from the ard drive. Both were erased but the EFI partition could not be erased or cleaned. Put this same hard drive, as an external USB, into a very old XP machine and there the EFI partition was removed when a "Clean" command was sent via command line.

I then took the, now totally erased hard drive, and put it back into the computer as an internal drive and booted the computer from a 10.8 USB stick so I could partition the now empty hard drive. The drive was not even recognized as being present. Did the same thing, but using the USB external connection for that same hard drive. It partitioned and then formatted with 10.8.1 (what was on the USB stick). After the OS was installed, the computer would boot using this newly created OS when connected as an external USB drive. Put the drive back in as the internal drive. Got a Kernal Panic. Forced shutdown and retried. Noi kernal Panic but drive was not even recognized. Pulled the drive from internal and put it back into the external USB and tried booting. System would not recognize the drive as even being present.

I then erased and cleaned the drive in the XP machine again and then, using the USB connection on the second computer reinstalled 10.8 from the USB. When I tried the now newly created software again, the same thing happened as listed above. 2nd machine booted fine on the drive as a USB, "Strange" machine booted fine using the drive as an external USB, Kernal Panicked then would not be recognized in the "Strange" machine.

It appears that when the drive is connected internally. it not only does not have the OS software recognized but will rewrite something in the drive that makes it impossible to be recognized by any Apple. My first thought was that the EFI partition was corrupted somehow so that was why I tried cleaning the EFI partition along with the other two partitions. But even with a new EFI and other partitions, the drive was not useable once it was used to try to boot as an internal drive in the suspect computer.

Now here I am dropping into speculation mode. My guess is that something in the very basic ROM (Pram?) that recognizes a hard drive is in the internal slot and tries to get to the EFI instead fails and in the process it screws up the EFI (or maybe even an address table?) in the hard drive. If it recognizes that there is no internal hard drive, it will happily boot from either a USB stick, a USB connected external hard drive or a Firewire/Terminal mode computer connected to it.

Sounds like a motherboard problem but I am wondering if it is possible to "flash" the very basic ROM that is at the start of the process back to factory default or maybe just replace the chip if it is the same one used as part of the Firmware password protection system.

Anyone have any other ideas or thoughts about possible solutions or at least a way to definitely identify what the problem's cause?