This bug has been in E2 for a long time, just bumped into it this morning by accident.

To reproduce:

Attach a DVD player or something similar, and have it play back, so that the scart signal is activated.
The option "automatic scart switching" must be enabled.
Restart enigma2 (e.g. using the web interface), and the box will crash, reboot, crash, reboot, etc...

Workaround:

Disable the autmatic scart switch option (not quite as handy) and set the box in standby to watch DVD.