Yeah just as I thought. It is because your profiles are on a different drive then what Windows is on.
The VSS makes a snapshot of the Windows drive and maps it to B:
As you can see here
--------------------------------------------------------------------------------
[13/11/2012 - 7:44:24 PM]
--------------------------------------------------------------------------------
13/07/2009 04:39 PM 383,562 bootmgr
01/12/2006 10:37 PM 904,704 msdia80.dll
15/10/2012 04:55 AM <DIR> PerfLogs
09/11/2012 09:10 AM <DIR> Program Files
10/11/2012 09:29 AM <DIR> Program Files (x86)
24/08/2012 05:19 AM 0 sniffer.log
13/11/2012 06:46 AM <DIR> Temp
21/03/2012 12:40 PM <DIR> Users
13/11/2012 06:49 PM <DIR> Windows
3 File(s) 1,288,266 bytes
6 Dir(s) 249,091,948,544 bytes free
C:\>start "" /wait "e:\Users\Peter\Desktop\tweaking.com_registry_backup_portable\files\vss_pause.exe"
--------------------------------------------------------------------------------
[13/11/2012 - 7:45:13 PM]
--------------------------------------------------------------------------------
The fallback method doesnt use VSS, it uses the Windows API to read the registry that is currently loaded. Thats why it worked for you, it doesnt matter what drive it is on it is pulling what ever is loaded. This is the same API that Erunt uses.
So just use the fallback method and you should be set
Shane