New XP [x64] install wont boot - [dual boot with x32]

I've had 32-bit XP installed on my system for a while and earlier today, decided to install 64-bit XP in a dual boot, each OS on a seperate hard drive. The installation seemed to go smoothly, but when I restarted the system after the install was complete, I get an error message telling me that (windows root)\system32\ntoskrnl.exe is corrupt or missing. My previous 32-bit XP install still boots fine however.

Can anyone please help?

 

Updated system details.

Okay, so I've just been trying out a few things which I googled.

1. Ran chkdsk /r using the repair option on the XP CD on the hard disk containing the XP 64 installation, no errors. Then ran bootcfg /rebuild and added the XP 64 install to the list. Restarted and booted okay from the boot loader into XP 64.

2. Quit XP 64, restarted then loaded XP 32-bit from the boot loader, 32-bit loaded fine.

3. Quit XP 32-bit, tried to boot XP 64 again from the boot loader, this time I get the ntoskrnl.exe error message again. Subsequent attempts to boot have the same result.

4. Tried running chkdsk /r and bootcfg /rebuild again, but still getting the ntoskrnl.exe error message after several attempts. Booted XP 32-bit and it's still loading okay.

I'm truly stumped. Can anyone advise on the best way to wipe my hard disks clear of everything, including boot records? I'm thinking I might just do a clean install of both onto the same disk (easier to back up), but I'd need to use the disk that currently has the XP 64 install on it.

Will full formatting in the XP install prevent any trace of old boot records potentially messing things up with a new install?