dan-572483 (10/12/2012)
Lesson learned: If you are doing massive changes to a large database that you'll want to reverse, use a full backup, not a snapshot.http://support.microsoft.com/kb/2002606
Dan
The article is very interesting but it doesn't seem to refer to the same issue that you were experiencing. If you have decided to use a full backup as your rollback process then fair enough but, if it were me, I wouldn't be relying on that KB article as the resolution to your problem.