Sounds like the Database got corrupted.
One of the easiest ways to check for that is to go to the status page which lists the dates of the database and in the lower right side shows the number of pilot entered waypoints. If that number is negative the database has become corrupted and all sorts of strange things happen. The easy solution is to switch to the expired database (or one to be used soon, the non operational one is what we are talking about) and then back to the appropriate database. That will reload the database and clear up the corruption.
Cheers
Wino