Quartus Fitter Crashing

This is not a response to the specific IE, but the ways you are seeing them move around.

Note that Quartus is deterministic, e.g. if you start with the same project on the same machine(and let's delete the /db), it will do the exact same steps and give the same results. (If you change anything though, even as little as the name of a signal in your design, or maybe add a comment, then all bets are off).

So internal errors should not jump around. When I've seen them, the user can repeat it and get the same one time-after-time. One thing I have seen when they jump around is corrupted memory on a machine. I hate suggesting that but throwing it out there.

One other thing I've heard might have an effect is the Number of Processors used. Maybe try setting this to 1 (I think it defaults to max available) and see if it becomes consistent.