Many of you may have seen the hype of the release of the new OS 3.0 for the iPhone. (http://www.apple.com/iphone/softwareupdate/)
Unfortunately, the upgrade to my phone broke my Exchange mail connection!
After browsing various web forums, and messages on twitter, many people found that their email, contacts and calendars synced after a while. This did not happen for me! So I decided to delete my Exchange mail settings, and then re-configure my Exchange settings. That did not work either! Phone hung on the Deleting screen for 20 mins.
In the end, I had to do a full reset on my iPhone. This process fully erases everything on your phone. I had to put my phone into DFU mode to do this (http://www.iclarified.com/entry/index.php?enid=1034 ). If you need to do this, make sure you have a full backup of your phone first!