I've been given a thinkpad t42. The original hard drive had died and they replaced it with an ibm 10 gb hard drive.
Now i've swapped another hard drive from a toshiba laptop, a 60 gb hitachi travelstar drive. I've put another 20 gb fujitsu drive from a hp compaq in the satellite a20.
The t42 won't boot win xp now. I know that's to be expected but instead of getting the usual stop blue screen after windows starts loading i just get a black screen with a blinking cursor. Ctrl+Alt+Del works. The data in the drive can be accessed from a mini xp boot cd, also it passes hitachi drive fitness test but it won't boot.
The same thing happens on the toshiba, i've tried paragon adaptive restore there first without luck. I use that when i move hard disks to a different machine and motherboard. I've tried the boot repair option as well (besides adjusting the os) but it didn't help.
I don't want to erase the hard drive, i want to repair the windows installation. I don't know what's going on. Any ideas? Thanks in advance.

I've tried repairing the mbr from paragon (fixmbr now warns about non standard mbr) and then fixboot from the recovery console, even repairing the windows installation by reinstalling but still the same.
I'm not even sure that formatting the drive would work. The data is still fine. Is this some kind of bios limitation?