IPhone :: Restore From Encrypted Backup But ITunes Does Not Recognize Password?

I was at a Genius Bar earlier today and they gave me a replacement iPhone 4. I had my laptop with me to transfer everything over and the guy working commented that I shouldn't use data encryption on the backup, so I said fine and he deactivated the option. I believe it was at this point that I was asked to enter the password, which I did. After a long time processing, there was an error message at the end. I wish I could remember what it said, but the guy said it should be fine. He wiped my phone I was returning, and then we set about to restore my new phone from the backup. Only problem is now iTunes doesn't recognize the password from my encrypted backup (this is the only one available). I don't know if something was corrupted during the attempt to deactivate encryption, or if this could be something else? I am positive I know the password—I entered it earlier in the process, and besides, it's the same as my passcode.

I was basically ushered out of the store because the guy said he didn't know what else to do. He just muttered some stuff about third party programs which Apple doesn't support which could retrieve data from a backup. I asked how those could possibly work on an encrypted backup and he didn't seem to have an answer.

Info:
iPhone 4, iOS 5.1.1