Hello.  I have two SATA INTERNAL Disk Drives in my Dell Optixplex GX280 computer.  The C: Drive (40GB) contained my OS and programs; the D: Drive (500GB) contained data only.

Tonight, I reinstalled Windows XP on my C: Drive.  I booted from the CD and verified that I formatted ONLY the C: Drive then reinstalled Windows XP. 

When I attempted to drill down on my D: Drive after bringing the computer up for the first time since the re-install, it told me I had to format the D: Drive (which I didn't do).  I thought that this may be due to Windows XP not being able to recognize large disk sizes so I installed SP2 and the same thing is occurring--it sees the drive, but each time I attempt to open it, it tells me that I have to format the drive.

This drive contains all of my data.  I haven't formatted it.  What do I NEED to do to get Windows to recognize this as a valid disk with data on it?

Thanks for your assistance.

Is there any way you could take out the hard drive and try it in ANOTHER computer? This will help us figure out if it is the hard drive or your PC.You need to MAKE sure it is jumpered as a Slave drive when doing this.
The diagram for this should be on the top of the HDD.