The user task bar at the top is showing an unread PM, however no unread PMs appear in any of the message lists. After a contact list invitation appeared, it showed 2 unread where it was 0 unread before, so that may have caused the discrepancy somewhere.

That's incredibly weird. Clicking on the Empty Inbox Folder link should clear the discrepency and wipe everything back to zero. I'll look into it.

I haven't seen it occur with any other recent PMs. Just seemed to be a fluke today. Emptying the inbox did reset it. Running Firefox if that makes any difference.

It has occurred again as a result of receiving a Contact List Invitation. Other PMs do not produce it.

I will investigate why the counter is wrong. Thanks.