I have just noticed that there are several of the "active" topics, here at phpbb.com, that are marked unread even though I have read them. this has occurred since the site was down for maintenance. If, on the other hand, I go to the topic via the actual forum it is not showing as unread. If, from the active topics, I click on the unread icon I am taken to the first post in the thread.

I had the same thing happen to me last week when there was a dip in the power and my PC rebooted itself. On that occasion I logged out and back in but it made no difference. I then tried deleting the cookies but still no difference. Finally log out, delete cookies, close browser, restart browser and log back in and guess what - still no difference. It was only when I refreshed the page some hours later that the unread icons disappeared.

see topic http://www.phpbb.com/community/viewtopic.php?f=64&t=532363