Blue Screen When Boot / STOP 0x0000007B

I have 4 or 5 year old Win XP Home Tiny desktop computer which is having trouble booting. Basically when booting up, right before the Win XP logo it reboots itself.I have disconnected all IDE devices except for the master hard drive (plus disabled them in BIOS), I have tried a different hard drive in the machine that I know is working and has XP Pro installed. The same thing happens with this hard drive - reboots. This hard drive also has Ubuntu installed, and the machine happily boots Ubuntu to the normak desktop, but for some reason won't boot XP!Also tried a third hard drive in this machine that is working with Win 2000 installed, again the same thing happens.

Next I tried the original hard drive in a working seperate machine which produces the same result again.Also tried removing the RAM from the original machine and inserting a stick of working RAM from my other machine which again makes no difference.All hard drives I've tried have the correct jumper setting (primary master).
Also tried putting the Win XP disc in the drive and booting to that, I get to the menu and try to do a repair (R), but a few seconds after the repair begins the system reboots (this is using the original hard drive).Also tried booting into safe mode, and last known good config on all drivers.The hard drive is being detected in POST and in the BIOS which I have set as the first (and only) boot device.When I turn off the auto reboot upon fatal error, I can see the blue screen of death with error code 'Stop 0x0000007B'.So looks like the hard drive might be knackered, but there must be something else aswell because my two other working hard drives don't boot XP (only ubuntu)