Where in ajax ?
Thirdusers is not anymore in use. Get rid of that.
In case if you want it, does the MVC triad (thirdusers) files present in your component ? Guess yes (sorry in advance for stupid question)
I think that all your recent problems comes from the loader. Missing files, or missing the auto-loader.
The auto-loader is very important because it permit to load the class files ONLY when they are used. The loader is only registering the class names and associates them with the physical file.
When you want to dirty fix such problem, just put a include_once() of your missing class.
But the best is to understand what the hell is happening. I was very to happy with the recent discovery, but now I a stuck again.
I want to follow closely this problem.
Did you tried to debug the loader ?
Cook furnishes you a dump() function in the loader superclass.
With this function, you can follow easily what is going on.