I seem to recall that duplicate AFDs also do that kind of crash. Were there any airports in the AI zone that have been added or modified?
If you deactivate EDDF and the flight goes okay, EDDF might still only be part of the problem, since sometimes there seem to be interactions between two addons, both of which work fine by themselves.
Also, can you get there with AI off?
Might also be worth travelling north from Stuttgart to see whether its a problem in the northern area and EDDF is approachable from the other direction.
Did the crash dump reveal which DLL was the faulting module? Graphics, AI engine, or something else.
The direct track is 85 miles so, if all else fails, at least it's walkable. Just take plenty of sandwiches.