Hello and welcome to Tom's Hardware Forums.
The most common problem I find with the Files and Settings Transfer Wizard, FAST or MigWiz, is where the source system has a different Service Pack level from the new system. If your USMT2.UNC folder came from a Service Pack 3 system, install that pack into the new system before trying to transfer the files and settings over.
If it's the other way around, uninstall the Pack from the target system. I hope it's this simple but if it isn't, you may have a corrupt folder so don't wipe the old hard disk just yet.