Reset it by holding the reset button in for 15 seconds. It is the small hole next to the AC adaptor connection which is next to the USB connection, you will need a straightened paperclip or similar to access the button.
I have had the same problem (3 or 4 times) and found just pushing the reset button mentioned above just for one push is all that needed to do the reset to fix the (stupid) problem of it not starting.
Great unit besides that "feature" and the on/off button (how hard it is to press!)
This has only started happening in more recent software versions. I never had this problem when I first got the rider, but about 4 days after upgrade it started doing this.
TomTom Rider not booting up
