I’ve been able to reproduce on multiple machines running the latest production version of FF3 on both XP and Vista…
I’m seeing problems in the Mark Read/Unread functionality. In Beta1, just cliking on the “Mark As” toolbar button would mark a message as read. Not only does that no longer work, but trying to mark a message as read or unread via that toolbar button/dropdown or by right-clicking on the message and selecting one of those options doesn’t seem to do anything. After trying, I’ll go to AllDocuments and verify that there’s no change.