I recently had trouble with my Maxtor HD as well. Except my HD was corrupted. First of all don't use Norton to try and repair the disk if the HD is corrupt!!!!! Use Data Rescue X to get your data back and back it up to CD then reformat your HD.
Ok see if this works. Restart with the HD unplugged then plug it in once your logged in. Open terminal type in mount to see if the drive shows up. Open up Disk Utility in OSX and if the disk is shown, repair the disk permissions and repair the disk. If it is not recognized boot into OS9 and open up Disk First Aid and do the same.
If this doesn't work, Maxtor includes a utility (Maxtor FireWire Software) with the HD. Start up in OS9 install this utility. Then use the Maxtor utilities to check the HD.
There are other possibilities to solve this, and it may be easier than what I have suggested. When I booted up on the OS X and OS 9 CD's the drives were always recognized (even if corrupted), and then you could repair it through the Disk Utilities supplied by Apple.
----->A thought for others, never buy a Maxtor HD you will only have headaches!!