And?

You have no question formulated, no info about what kind of system, what problems you are having causing you to run diagnostics, and you don't mention what part of the diagnostics it's running when this error comes up (cpu, memory, harddrive, cdrom, etc).

Am also getting this error code.  Did a diagnostice as the computer is running very slowly.  Memory tests all pass but this one hard drive test failed.  What does this mean?  What should I do?  Computer is a Dimension 2350 out of warranty.

On the GX260 during the post process you can press Ctrl+Alt+D and it should initiate a harddrive test. This test should take 90 seconds or less. If it fails too, you will need to replace the harddrive. If the system is under warranty, call Dell. If not, you can buy any ATA drive from any store. The GX260 shouldn't have any problems with large drives (older systems don't always support drives over 137GB). The only thing to pay attention to is not to get a SATA drive as you would need to get a controller card. One little note is that if you buy a drive, be sure to jumper it for "Cable Select", not master or slave (see label on drive how to jumper it for this).

The Dimension system can likely run the same diagnostics in the same way.

If the second test does not fail, what does the error indicate?  Would a re-format fix it?  In my case the drive seems to be slowing and I'm seeing some odd problems, but the 0F00:0244 error during HD diagnostics is the only indication of a problem.