This could be one of those random unsolved Outlook mysteries but I'll ask here. Every once in a while our users will get:
"item cannot be displayed in the Reading Pane"

..and the reading pane is greyed out. I see plenty of matches from google, but no fixes, yet. I defiantly want to spend more time on this to figure out if this is:
1) a random lame unsolved Outlook problem
2) a fixable problem
3) caused by the Outlook Connector
4) a problem between Outlook and certain add-ins
5) seemingly caused by the Outlook Connector but some sort of design flaw or limitation of Outlook

At the moment, I'm guessing it's #1, #4 or #5, but I'm still searching for any definite fixes.