Seeing as it is not happening all the time, is there something specific that you are doing that might be the cause.

Example #1: Sometimes after reloading a Captain Sim aircraft many times, I have this happen. I exit and restart FSX to get around it.
Example #2: Loading the Captain Sim aircraft into FSX after using a different developers aircraft. Again I exit and restart FSX to get around it.

So unless it is when you first start FSX and the CS707 is the first aircraft you load into FSX, it could be one of the above cases. You didn't specify whether this was the case, so I'm describing what has happened to me.