When the valid group authenticator credentials fail to install the device, the following error message shows:
Unable to verify the user name/password provided. Please check your entries or contact your system administrator for assistance.
The Dell hidden partition is the first partition on the machine and it is also marked as the active partition.
To resolve the issue:
- Go to disk management, right-click the C: drive and select Mark Partition as Active.
- Reboot the machine. You should receive "BootMGR is missing".
- Insert a Vista install CD and select the Recovery Option.
- Do an auto-repair when prompted.
- Select Advanced Recovery.
- Enter the following commands: bootrec /fixboot
- Reboot the machine. You should now be able to boot into Vista without any issue. For more details in using Bootrec.exe in Vista, refer to the Microsoft article Use the Bootrec.exe tool in the Windows Recovery Environment to troubleshoot and repair startup issues in Windows.