i can't remember, but i think that is caused by winterboard, and the actual safe mode itself is MobileSubstrates way of saying something went wrong.. reboot and you'll be fine.
i have this still after installing lockscreeninfo and it wont go away! it was after an apparent update to support 3.0.. i have removed my lock calendar which might of been conflicting but no joy... and i cant ssh to fix the prob because you cant when in safe mode!
Just remove Lockscreen Info until the author fixes it. I had same problem.