If it's under warranty call or contact Flip Video (division of Cisco): http://www.theflip.com/en-us/support/ (try the 24/7 chat)
If you out of warranty or too impatient to call support here a few things:
RESET BUTTON on Flip Video
from youtube user http://www.youtube.com/user/glenwoodfin
REMOVE BATTERY (try to reboot the bios).
A solution to the dreaded charging error of the Flip Ultra Hd.
Steps from youtube user http://www.youtube.com/user/MYOLDNEIGHBORHOOD
1. Take battery out of camcorder.
2. plug camcorder in computer.
3. once it is connected and the computer recognizes it (either you hear a sound, and or it goes to autoplay) place battery in camcorder. (the batter that it came with)
4. safe eject camera. You know its safe eject if there is an icon on your notification panel on the bottom right hand of your screen. (windows)safe eject means to right click on the safe eject button in the bottom right side of your screen on your computer and then click safely remove hardware.
5. plug camcorder back in and let it charge.
6. pray it works. It will!!!!!!!!!!!