Hi Sam
We have been investigating this and our Bry has figured it out, but you aint gonna like the diagnosis...
It looks like the problem is related to windows not Videobox, the 'user.config' file is the cause of the problem but the file is handled by the windows operating system and it can become corrupted, just google 'user.config corrupt' for a million people reporting this problem
.
Our Bry thinks it's a corruption in the config file xml, probably caused by improper shutdown of the program or PC.
We dont know if there is an answer to this yet but our Bry has told me that he has some ideas & some avenues to peruse, so there may be a workaround, watch this space.
In the meantime, If you encounter this problem you can quickly get working again without re-installing, simply delete the corrupt 'user.config' file and Videobox will write a new one for you.
Steve