VSS error 8193 Unexpected error calling routine ConvertStringSidToSid fix

I you get this error you need to find the .bak sid in the error code

so for example
Volume Shadow Copy Service error: Unexpected error calling routine ConvertStringSidToSid(S-1-5-21-2747290079-2543033363-2118852912-1197.bak).  hr = 0x80070539, The security ID structure is invalid.

the sid is S-1-5-21-2747290079-2543033363-2118852912-1197.bak

Then go into registry

HKey_Local_Machine\Software\Microsoft\Windows NT\CurrentVersion\ProfileList

Delete key after backup
reboot, see if problem goes away

http://social.technet.microsoft.com/Forums/windowsserver/en-US/7b52f7c1-a783-409e-9af3-da64567676df/vss-error-8193?forum=winserverfiles