need to download the latest firmware, which isn't appearing in iTunes, apparently this will solve your problem.
Basically, Restore your iPhone, and it will offer to back it up - you then need to say OK to all the prompts.
It should start downloading the firmware in iTunes and then proceed to load all your data onto the phone again, ETC.
Apparently this solves your problem, but i've been unable to download the firmware (I'm getting a -3256 error).