The screen on my tomtom keeps going to a blank white screen any ideas

SOURCE: TomTom GO 720 - flashing red circle with white cross on screen

Hi, I am back, just got the problem solved, I called their tech support at no charge (866-486-6866, Glen) , really good service.
First turn your firewall off (if you have one). You need to go into your 720 with the TomTom Home software and erase the downloaded software (with the remove items from my device) and reset the device (little reset button under the unit keep it pressed for 5 seconds), place it back in the cradle and restart your computer and than restart the 720 , bring the TomTom Home program up, and when the TomTom Home software in your computer restarts and detects the 720 it will tell you that you need to update the application, if it doesn't than you force the update by going to the add maps option, select items on my computer, select applications and press the add button, when done, go back and to device (option in top of your screen) and select disconnect device, restart your 720 and it should be back to life with the upgraded software.
Hope this helps
Aldo

SOURCE: blinking white blank display after turning on

Try resetting your tomtom by inserting a paper clip through the reset hole found underneath. One quick press is all thats needed. Charge the tomtom first now and then switch on after its had a good charge.
If this doesnt work , please reply again and i'll try and help further.

Good luck

SOURCE: tomtom 1

You cannot use a sd card from another tomtom. The sd card is coded for each individual device. About the only thing you can do is to purchase a 1 gb card (no larger because it won't be supported). Insert the blank card into your unit and connect it to your pc. Go to my computer and see which drive the tt is. format the card and then open tomtom home. This will load your operating system back onto your card. I don't know if you can download a free map or not. Check the tomtom forums for more information concerning maps.
Hope this helps