same here..
have searched whole nights for this issue , was happily on 3.1.2 on 3gs new bootrom ,
i havent upgraded to 4.0 , but something went wrong and the phone got stuck on itunes logo , black rain wasnt working and the phone always stuck on geohotz picture...
now i try to restore the 3.1.2 firmware...and guess what....apple doesnt allows me
tried restoring to 3.1.3 ...and guess what....apple doesnt allow me again....
APPLE HAVE STOPPED SIGNING FW 3.1.2 and 3.1.3...
so i got no other option but to upgrade to 4.0 when the jailbreak arrives..
so far no solution....absolutely no solution....
BTW..snowbreeze 1.7 is out...