Windows cannot load the device driver for this hardware. The driver may be corrupted or missing. (Code 39)

I have a Quantum SuperLoader 3 with a Quantum LTO 3 tape drive on a Windows 2003 Server.. We were having backup speed issues (it was going slower than usual) so inside Backup Exec we did a "Tools > Wizards > Device Configuration Wizard > Install tape device drivers > Uninstall and remove all Symantec device drivers for all devices on your system" because we were going to try the Quantum drivers to see if our backup speed would increase..

Ever since doing this, the backup devices show with the yellow exclamation points in device manager. We've tried uninstalling, scan for new hardware (it adds them but they still have the !), we've tried uninstalling and manually selecting the Quantum drivers (it adds them but they still have the !), tried rebooting after uninstalling and letting them add themselves (same result)..

I'm running out of ideas.. Like I said, they were working fine, and showing up until correctly until we did the above..

Thanks for any help!