gimagex - Error: Unable to mount image ???

I was trying to mount a wim image using gimagex and was getting this error - Error: Unable to mount image ???

I did some digging and found the following -

1. Make sure GImageX is closed. Open Regedit.
2. Navigate to "HKLM\Software\WIMMount\Mounted Images"
3. You should see a subkey with a long name like "374cf018-f245-442d-9544-d6a2092607e0". Delete this key. (Don't worry about deleting this key, it should have been removed anyhow)
4. Close Windows Explorer and reopen it. Delete the folder you used as your mount point (eg. "c:\mount"), then re-create it.
5. Restart GImageX and the image should open correctly again.