Is it possible to restore a backup made today with the latest 4.2.1 software, on a 3G iphone that has been downgraded to 3.1.3 ? Got sick and tired of the slooow speed and downgraded and it's as fast as it used to be (even faster than the latest 4.x software). But now I can't install my backup. I can't find any guides with a work around and fear I'm screwed. Is there any way to make it work?