Accessing Flight Plan causes crash - after 1 flight

Hi, I have a strange thing that has been happening for many months, so I'm not sure when it started.After loading up FSX and flying a flight with The Airbus or 737 PIC planes from Wilco, where I have loaded a flight plan into the FMC and flown the flight to conclusion, I cannot load a new flight plan without a crash to desktop.This happens if I:1) Try to load the flight plan into the FMC using 737 PIC after making it the active plan in FSX2) Try to access the flight plan on the Kneeboard, so I can manually enter the waypoints into an FMC.Sometimes this only happens after a few flights, and instead of crash to desktop, I get "Flight plan not found" when I try to import it into the FMC of any plane, or when manually entering waypoints, no waypoint identifiers are recognized and all do not exist. I can type in NORMY or SEA and the FMC will know nothing of the reference. It's like my navigation data gets overwritten in memory, or something.Any thoughts?