I think there is a glitch with the Private Messages section. I continue to have the same 2 PMs show up on occasion, even though I have read them. They happen to be best answer PMs.
If I answer them enough times, they will finally be listed as read... for awhile. But, then they are back again as un-read.
Seems somebody also let the 404s and 500s out of their cages as well. Better call animal control or whoever is supposed to handle escapes as they're running loose everywhere. Heh.