I should add that running the pc check up from dell support center, it checked the drive - no problem seen

same when testing the usb devices from system summary (dell support system)

latest update:

in computer management under device manager, I can see the external hdd along with the internal

if i try to update the driver for the drive, it says it is up to date.

but under other devices section there is an unknown device (with the yellow exlamation mark)

if I click on property, under device status, it says:

'This device is not configured correctly. (Code 1)

There is no driver selected for the device information set or element.

To reinstall the drivers for this device, click Reinstall Driver.'

but windows is unable to install the unknown device...

You should try the Maxtor help site or the WD web site--WD has a better FAQ section that can apply to all makes of hard drives. The Unknown Device is something else, not the external drive. External drives only appear under Disk Drives and you say it is listed there. On my Vista computer I had that unknown device for the Game Port on the video card that had no vista drivers available. I disabled it to remove the Unknown Device message. Make sure the drive formatted correctly in NTFS. If your other computer has windows xp, the drive might be using the FAT file system. Look at the properties of the drive in Device Manager or Disk Management. Look up Convert FAT to NTFS in windows help for info on how to change it.