Hi there
I have had this issue all the time, I tried to restore SBS 2003, XP professional and home images which got password onto a duplicate or a differential hardware system. all of them failed to restore MBR.
I tested it, the outcome was MBR sucessfully restored from the image which got NO password, but the one with password keep failing, even the backups are exatly the same content.
I tried different restoration options, such as restore MBR from image file or restore original windows XP file. neither of the options will help.
keen to get anwsered, Cheers!