Medieval II Total War .net framework error.

So I recently bought that Gold edition from GamersGate.

The game started with a .net framework error.
I could still launch the game but I could not play the Teutonic mod.

Hence, I opened a ticket. The instructions I was given did not fix the problem.

Having looked around the web, I found exactly what could do the trick.

Here is what is needed in case others would be confronted by the same situation.

In short, it's the launcher that is at fault. The new launcher fixes everything.
It's like a nexus mod manager.