Hi at work we use a public calendar in Outlook 2010 that is used to book the conference room. Today multiple users (XP and Win 7) are getting this error when they try to book the conference room.
The operation failed. The messaging interfaces have returned an unknown error. If the problem persists, restart Outlook.
Restarting Outlook has not helped. So far this is only happening in the public calendar. Any help would be appreciated.