Marking messages read prematurely

Factual Questions
1

I’ve noticed this a few times now. I checked the boards shortly before going to bed at 03:00 EDT (02:00 AM board time). When I woke up at shortly after 13:00 EDT (12:00 PM board time), my mail said that some threads had been updated. I went to check them, decided not to comment on anything yet, and went off to read the news and such.

When I came back half an hour later to load up the fora I read, everything posted prior to the time I checked that one thread had been marked read. Yes, everything posted up through 12:10 PM was marked read, when I had only opened one thread since 02:00 AM board time. I can easily find which threads have been updated since I last saw them, but on some of the larger threads it’s nearly impossible to tell which posts are truly new when viewing in threaded or split mode.

Why do the boards mark all these messages read and torture me so?

2

I’m bumping this because it’s happened a couple more times. Sometimes when I write a message (maybe it’s when I’m taking a while to write it), the boards mark all messages read up until that time. This is getting really annoying when I want to go check what’s new on particularly long or involved threads. Will someone tell me what’s going on here?

3

The board software logs you out after something like 10 minutes (IIRC) of inactivity. If you are cookied in, clicking a link after that time period logs you back in automatically. The software assumes that any threads prior to this point have been read and marks them accordingly.