Was flying a ship on a server. Suddenly, I was hit with the "Ship overheating" message. No damage to ship blocks whatsoever, no damage to ship HP.
Ship inaccessible. Reboot dialogue works, returns a "30 second" reboot time. Reboot will reset HP if one intentionally damages the ship afterwards, but it will not stop the ship's overheat timer.
Uncertain if it's possible to reproduce this intentionally.
Image of overheat timer below. Note that damaged HP was intentional, in an attempt to determine whether causing ship damage would make it possible to reboot successfully.
http://i.imgur.com/cAk2cv7.png