[1.1.1 (1.1.2)][Problem] Black screen!

Hi
I got an activated and jailbreakbreaked 1.1.2 OTB, everything except calls/sms was working great, until i accidentally placed a call to a contact.
My screen just showed "No answer" and i could get no contact to the iPhone from there. Finally i pushed the "Power off". And now, when i push the "Power on", i get the usual "Slide to unlock", i slide, and are presented with a black screen, only an arrow at the right bottum and batteri status, clock and wifi status at the top.
Nothing happens, i have tried pulling out the AT&T sim card, still no reaction.
Does anybody have an idea of what to do? i can still browse the phone via WinSCP.
Forgot to mention, synchronizing from Itunes still works