HP6515 TTN6 SD Card problem

Hopefully someone can help me

purchased new 6515 with TTN6 on SD card - worked fine for first 5 days but now when I insert the sd card into 6515, comes back with "'Tomtom navigator' is not a valid PocketPC application".

Have tried uninstalling app, dowloading update from TT Home, and soft/hard resets of 6515 - none of these work

also searched TT CD provided but could not easily find a complete install set of files to overwrite SD card - so didn't

now I'm just depressed :-(