This usually means that the maps have not been verified or that the SD card has lost the information, if you have a backup up on your computer, try restoring it from the computer using "TomTom Home". That will usually work. If you have not backed them up, then contact TomTom see what they can do. One other reason, may be that you have put the wrong SD card into the TOMTOM.
Bigboab, January 2009