Bear in mind that Windows 7 backup will not make a whole system backup unless the backup drive has a higher capacity than the system drive. If you have a 500 GB system drive with 100 GB of files on it, Windows 7 backup will not back it up to a 250 GB drive. A bit strange.
You can use Disk Management re-initialize, partition, and format the drive. If you don't have admin access to your own machine (a bad position to be in), you can download Parted Magic, make a boot CD, and initialize the drive with that.