I'm posting here in response to CS's request. I wanted to reply to the suggestion that slowing the speed of input into the FMC would prevent the CTD from happening. I tested this pretty well last night in FSX, but still had the CTD. The particular crash I had was when I went to input a crossing restriction at SMO on the SADDE6 into KLAX. It crashed right as I put the 7000 into the SMO line of the flight plan. So I wasn't even doing an exec, just inputing the restriction.

One other point is that I had changed the arrival runway from what I originally had on the flight plan. I did this and exec'd it well before inputing the 7000 and CTD. I don't know if that could be a contributing factor in the crashes.