I'm running two hard drives on my PC and i"m trying to re-install XP pro to both drives due to some nasties I can't rid myself. I'm installing with a XP pro upgrade CD. (My upgrade CD wont allow me to boot from the CD drive and install so I have to install to slave drive first than switch masters and install again) I can install to the slave drive with no problems. but when I switch the jumpers and try to reboot I get an error saying "invalid partition table". I've tried formatting with both NTFS and FAT formats but I get the same results. At start up the BIOS is recognizing that the new install is the master and the other HD is the slave; so i feel reasonably confident that I've got the jumpers set correctly. What am I missing? I've read that this error can be caused by having more than one partition active. Could this be my problem and Is there something that i can adjust in the master boot record?