Outlook is marking my messages as unread when I click on them

[onishaw]

I am used to Outlook marking my unread messages as read as I view them. However, over the past few days, whenever I click an already read message, Outlook is marking them as UNread. I have gone through all my settings to see if I inadvertently changed a preference somewhere but I don't think I did. (I can't imagine ever wanting this as a preference choice anyway since I now have to right click every time and choose "mark read".) It seems to be happening with my SMTP accounts and not my POP accounts. Also, once I have revisited the email twice and let it be marked "read" a second time, I seem to be able to go back it time after time without it getting marked unread again. I hope this sounds confusing as it is. And it has only been occurring the past few days and only on one computer. I am stumped! I have restarted outlook. Rebooted the computer. It is independent of which network I am using. And I cannot find any reference of anything like this happening to anyone else in a web search.