MEP problem

[NandoMogollon]

I'm having a problem here with the MEP:
We only have 3 dongles licensed to work with it, but we have installed the MEP software on another computer (that means 4).
If I open and save a pln from a Mac using AC with MEP, using a dongle licensed for AC but not for MEP, then no one with AC but without the MEP installed can open the file. Even that in that specific file we never used MEP objects or tools.

It is not a single situation, it happens with every pln saved from a Mac with MEP.
All the AC installed have the same add ons / goodies, library updates, and are updated to built 2420.
When we try to open the file this is what it shows:

[Rakela Raul]

even if you click 'ignore error' ?

[NandoMogollon]

Yep, and then it opens a completely new file... "untitled.pln"