+ 0 Votes this should fix the problem. Space Coyote 7 years ago svanarsdel on techguy said:"The workaround is to remove the attendee from the meeting. Then Save & Close, but DO NOT send an Update. Then readd the attendee who was having the problem, Save & Close and DO send the update this time. The attendee should receive a new invitation and shoud also be able torespond to it without the error message. If it is happening to all attendees, I would remove the Outlook Address book from the computer requesting the meetings and then read it."- Space Coyote + 0 Votes Perm fix dchandler 7 years ago Is there a permanent fix? + 0 Votes This should help if you still have the issue R.E.SMITH 6 years ago Check out this linkhttp://www.outlook-tips.net/howto/commandlines.htmGo onto the users computer and go to start, run, and type in outlook /cleandmrecordsoutlook /cleanfreebusyoutlook /cleanprofileThis cleared the issue for me.