HrClausen
I read somewhere a suggestion that autofocus should be locked before zooming.
FWIW, this definitely isn't recommended as a general rule, although may avoid problems on certain ports.
I assume when you tried without AF Lock, the camera was in regular AF Mode?
When you zoom, are you using key presses, or using set_zoom? The "PressTeleButton" in the log suggests it's key presses, but normally zoom related crashes only affect CHDK set zoom. Scripted key clicks should really be no different than pressing the physical key.
What shooting mode is the camera in?
Have you tried reducing your script to a minimal test case? Just turn on the camera, switch to rec, zoom, without anything else?