I couldn't get OWA to work from behind our firewall so I made a lot of config changes to the IIS OWA sites. Finally figured out the problem, but the security was so messed up that it wouldn't let me login. Followed the MS directions on unmounting the information store, removing IIS, reinstalling IIS, reinstalling Exchnage, remounting the stores. Did all that. Getting a 500 error when I try to launch OWA. When I go to the properties of the ExchWeb or Exchange in IIS, they all say "You must select a valid application pool". Not sure where the install went wrong....