My iphone 4s was on 5.1.1 when it stopped getting service randomly. I didn't get any prompts when removing or putting the sim card back in, but tried the sim in another phone and got service. Tried to re-install ios 5.1.1 via redsnow and it gave an 'itunes error -1'. Now its stuck in the recovery loop and I'm unable to get it out. I tried exiting recovery with redsnow as well as tinyumbrella, on 2 different windows PCs and 2 different macs. Tried putting it in DFU mode and restoring with both itunes and redsnow, still get the same problem. Depending on what I've tried last to fix it, my iphone will either show the 'plug into itunes' picture, show a completely blank screen, or get stuck in a loop where the progress bar comes up and its continually trying to update the firmware. I saved my SHSH blob for 5.1.1 so I tried to restore for 5.1.1 as well as upgrading to 6.0. -1 error on both. If anyone has any suggestions I would be very appreciative.