Found a bug, not sure if anyone encountered it already. But while I was trying to figure it out, I tried searching for this error and couldn't get any help. I eventually figured it out on my own.
Here is the error:
Your Firefox profile cannot be loaded. It may be missing or inaccessible.
>
Here is my environment, not all of it matters, but I will just put it anyway.
Here is what leads up to the problem.
Here is the discovery of the problem.
Other interesting discoveries about the problem
Easy Fix
Plugins need in general to be installed under admin priviledges in windows. If not installed this way, then chaos may be the result.
In fact, the installer should even prevent any installation of such plugin if admin rights are not given.
This is probably a bug in the plugin installer itself.
Otto Sykora
Basel, Switzerland