I have had an iPhone since the first gen came out. I now have a 3G and I have never once been able to upgrade my software without an unknown error and then my phone is stuck in restore mode. Last night I finally disabled my AVG anti-virus (free version) before running the 2.1 update. The update went through perfectly on the first try. I do not know if other anti-virus software has the same effect. I also disabled windows deffender just incase as well. Hope this helps.