OS X Kernel panic.

This morning, I fired up my computer, and went downstairs to get the coffee macine brewing.
When I came back to my room, I didn't see the screensaver in action, but a black screen and a unresponsive computer. Had to power-recycle to get it going again.
I then went to take a shower, and when I came back: same black screen etc...
Thinking it might be BreveCreatures doing this, I went into preferences/screensaver settings, but when I tried to open it, instead of displaying the screensavers, it froze and I had a kernel panic.

I didn't have much time (train to catch) so I switched off the machine.

This evening, some more time, I restarted, and using the 'hot corner' to trigger the screensaver into action, same result.
Now I had a saved version of breveCreatures.xml from an older 'run' so I thought, maybe swapping out the existing one with my saved one can solve things, and hey, whaddayaknow: it did!
But... I can't re-create the problem anymore, by re-replacing the 'corrupted' XML file...

So I'm a bit at a loss what exactly was the cause of this....

So... corrupted .xml file...