Cavalry external HD on Windows XP Pro...

*New (virgin) Cavalry 500GB USB external HD not showing up in "My Computer" and not usable...
*HD shows up in Device Manager under "Disk Drives" as "working properly" and is "enabled "...
*HD shows up in Disk Management but does not have a drive letter OR does it show a file system such as "NTFS" or "FAT32 "...
*It DOES allow me to ADD a drive letter, but when I do, it still does not show up in My Computer...
*When I attempt to format the disk (NFTS) from Disk Manager, it will not complete the process and gives me a pop up message stating that the drive must be "enabled ", and to enable the drive I must restart the computer...
*When I restart the computer same thing all over again...no letter...no file system...
*Tried different USB ports...same
* Cavalry support says it sounds like I'm doing everything correctly and to ship the drive back to them (California) at my expense I might add, and they will send me another drive...
*Any thoughts or ideas before I go that route would be appreciated.

-Vic

ETA:Update...!
Plugged the HD into another computer and it formatted and works fine.
Obviously something amiss in my puter...I'll keep looking.
Arie...thanks for the reply