this has happened to my mutltiple times.
the first 3 times it was forced into reboot, it was bricked (luckily i hadnt spent the time syncing music/vids) and restored.
after the 3rd time, i did a COMPLETE erase of content and settings (which took 2 hours, and i didnt mind)
the next 4 times i think, it was forced into reboot, but came back.
for those that are getting bricked, try COMPLETELY wiping content and settings, for me it helped prevents future 'bricking'