get into safe mode with ios5 with no safe mode apps or sbsettings.
well I'm a iPhone app developer and today i jailbroke again after like 7 months, and i got this 1/4 screen thing and everyone says safe mode and exit fixes it. but i had no sbsettings or anything besides respinging. so if anyone else ever get this problem just do this. first off you must have something to atleast respring. go to however you respring, and respring the device. as soon as it starts just press home over and over and the power button just randomly. and it will crash into safe mode. then you fix your issue