I have a Tom Tom 910. It was working fine and then one day it just locked up on boot up. A large red X appeared in the bottom right of the scree. I did the reset with the paper clip and plugged it into the computer with the cradle. Not it starts to boot and then there is a dialog box in the top left corner that says "formatting failed" and the screen is locked with an hourglass on it and a hand with a red cross through it. The computer says that it has errors and can't be recognized through the USB. Any Suggestions.

SOURCE: how to reset tom tom 910

i can not see the reset switch help

SOURCE: Tom Tom XL stopped working after plugging in USB

You need to reset it, by holding in the reset button for 15 seconds. If there is an SD card or memory card of any kind, take this out first. sometimes you have to use something sharp like a paper clip, and push it into a small reset 'hole' in the back of the unit.
then put the memory card back in. then look online for step-by -step instructions, usually from the vendor, on how to update the software, if indeed it is at all necessary. Also, try doing the update on a PC instead, there's a chance it's not supported for Macs. I know this is controversial.. i hate Windows too.. :)

hopefully the reset button will resurrect yr tomtom though.
good luck

chris

SOURCE: favorites button greyed out on tomtom 910

when you update the maps favorites are erased the favorites will also remain greyed out untill you have marked atleat one address or location as favorite

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

http://www.tomtom.com/support/index.php?Language=1&query=red+cross&FID=1898

SOURCE: 910 frozen

Red cross issue:
http://www.tomtom.com/support/index.php?Language=1&query=red+cross&FID=1898