When attempting to re-image a computer with Windows 7, an "Access Denied" or "Master Boot Record Permissions Error" is encountered.
This is due to the way that WinPE 3.0 handles volumes.
To work around this, use the WinPE 3.0 'Clean' function to remove all volumes from a drive.
1) Boot into WinPE 3.0
2) At the command line enter "diskpart"
3) Enter "select disk 0" (or other disk number, if applicable)
3) Enter "detail disk" to check to make sure this is the disk you want to be removing the volumes from (in case more than one disk is installed in the machine)
4) Enter "clean" -- This removes all the volumes on the disk.
You will now be able to re-image the machine.