I have a computer that I want to get up and running, it was working fine then a major event happened, I don't know what exactly but one day it worked then the next it didn't, that kind of scenario!! Ghosts or whatever. Anyway, I took the hard drive out and reformatted and partitioned it on another XP computer but when I go to re-install on the original computer it stops during the setup part when it gets to the partition bit - it comes up as unpartitioned and if I push C to create a partition nothing happens. So it's been successfully formatted and set up on another computer but when I try to get it running on it's own computer suddenly it's not formatted. ??
I would suspect that the BIOS settings in the computer where you are trying to install XP don't match the settings of the PC where you formatted the drive. This can happen with a SATA drive where you can choose between AHCI addressing and IDE emulation. The two are not compatible.
I would suggest trying again to format the HDD in the PC where you want to install XP. Try different BIOS settings for the hard drive and see if you can create a partition successfully. Then you should be able to format it OK.