I did all the things you mentioned and now have no video showing in the source software at all. It's just a grey square where the video should be. My devices aren't showing anything.
I reinstalled the source software. Ran the registry cleaner file and installed the software you mentioned.
I've checked the webcam and that's working with other software.
I'm a bit gutted.
UPDATE.
Ahem. Scrub that. I er... Needed to log into the source programme again. It's up and running. It needs to run a few days before I'll know if it's cured or not.
Thanks very much for your help. And sorry for being so dense. I blame google.
Sadly, this hasn't worked. It ran for about fourteen hours and then came back with the same message. It just won't run continuously. I can't always get to my PC to restart the source software. Beginning to wonder if maybe I should look elsewhere for something similar. Thanks for trying anyway.