navigon gps


I own a Navigon 5100 and am having a problem with directions. I am instructed to make bizarre turns. When I know that going straight is the proper way to go, it tells me to make a right turn. It sometimes tells me to make a U-turn on a highway! What is going on and how can it be fixed? I have been instructed to make a turn on the next street which is not there!!! HELP!