This is not really a problem to me, but may be a bug.
On odd occasions the icons net to the forum posts change at will!
This may be my connection, or something else. An example:
This morning I scanned through the PHP forum, and there were about ten posts
where the icon said 'NEW', so I read one, and when I went back to the index page, all the icons had
the 'read' symbol, although I'd only read one..... Strange....
Right ... individual threads are considered read if the forum they belong to has been read. If you read the latest item in a forum, that entire forum (and, consequently, all other threads in that forum) all become read.