Intermittent problem with saved .rte files

I am getting problems when loading in saved flights. The following message appears - "Destination not found in selected .rte file. Import aborted.". I have looked at the the .rte files concerned and cannot see any difference between the ones that won't load and those that do.

I flew EGKK to LOWI with a -800 and saved the flight a couple of times. Each time the flight loaded OK. When returning LOWI to EGHH, I saved the flight a couple of times, but got the above error message when trying to load the flight in.

Any advice, guys?

Chris Hall