try to remove any software like kate which mess with the springboard, kate has some major problems wit the devce..
try to download a software called free mem from itunes and free up some memory..

when u restore/upgrade make sure u know which iphone baseband you hav as the newr basebands cant be unlcoked it would require something like rebel sim or turbosim..

if u have a rebel or turbo sim..upgrade while the sim is removed and then jailbreak with quickpwn and den try..