I wanted to post a solution that Pablo told me regarding fixing the iTunes backup problems. Pablo found that when he changed his time zone (he didn’t mention what he changed it to), the sync and backup problems were fixed. This is what Pablo wrote:
To fix the “iTunes could not back up the iPhone because the backup session failed” bug found on itunes 9.2, you have to change your computer TIME ZONE and you will be able to backup witn no problems. This little trick fixed my two computers, one with XP and the other with Windows 7.
If this works for you, please let me know (post a comment) and thank Pablo for telling us about this.
You can find Pablo’s comment post here: https://cgatesmobile.wordpress.com/2010/04/24/itunes-syncserver-summary/#comment-105