Hi, is the drive "empty" or does it contain partitions already ? I know, that sounds like a stupid question. but I have to ask.. ^^
In case you have got access to another IDE equipped computer, you could try to use one of those drive erasing software.
Like Acronis' drive cleanser or similar. Perhaps it is already enought to clear track 0 to make FDISK work again.
Anway, that's just an idea. I've got no tandy machine right now. Perhaps they require extra steps I don't know of.

Well I got it to work by connecting to modern computer and wiping the hard drive clean! However I can not get it to boot Dos from hard drive at all. I have to boot from Rom or Floppy to get anything going. Also certain programs and games that used to work fine now won't load correctly or load at all but only when the Xtide card is installed. When I take it out all programs work as they used to.

I got it to boot to dos! For those interested..here is the response i got from the user "Soviet" on AtariAge that got me going:

"Try to write 0000 to it on the a modern pc and then on the tandy do a fdisk add the partitions and then do a fdisk /mbr to replace the mbr.
Make sure that the partition si active shows the A before the partition.
Then do the format c:/s to get the system on it i´m using dos 5.0"

At this point I am booting into DOS 5.0 from the hard drive on a Tandly TL/2 using the XTIDE IDE interface and a SATA hard drive with an IDE adapter.

Still the issue where I am unable to load properly or load at all some games is there however. Still looking for a solution to this if anyone has any ideas??

I have an XTIDE running in my TL/2, but it's the cut down XT-IDE CF version that only supports PIO.
More info here: Tandy TL/2

Your problem sounds like a resource conflict, or data corruption.
I think the full XTIDE supports DMA and/or IRQ? Can you switch it to PIO only at D800h or CC00h?

I had some data corruption problems with my XTIDE that went away when I changed to using a CF DOM like this one:
http://www.ebay.co.uk/itm/32MB-DOM-Transcend- … 1UhVEPLsCTCNPVg

Symptoms were random hangs on disk access and occasionally when booting DOS.

I did get the games to work finally! After reading the universal bios wiki I seen that some Tandys require that the "full" feature be turned off in the bios. Did that and back to normal. However, I cannot get my mouse to get recognized. Unable to install the driver. Says it is not found even though it is plugged in.