I ran into an issue with XpressMail which required a hard reset of the phone (reinstalling WM6 from internal ROM, losing all installed software, contacts, calendar, etc). At least, it was required according to the AT&T Customer Service Rep ... It was a serious pain to reinstall everything, but I suppose any little hacks and tweaks I did to the registry that shouldn't have been made are all corrected now ;o)

Thank goodness for the Plaxo Sync application to reload everything that it pulls in from all of my various address books and calendars at Google, Yahoo, Hotmail, etc., etc.