Not dumb at all to ask such a question. I asked the same one when they reported it. <img src="https://www.ubbcentral.com/boards/images/graemlins/wink.gif" alt="" />
I’ve had enough experience with “user error” to never assume anything.
At least one member did hit refresh that I know for sure to no avail. This guy is a programmer and also knows his way around a web page. I was suspicious of the reports until I got one from him. In all, four members have reported experiencing this behavior more than once.
I had a very minor hack installed that allows the PM notification to appear on the Active Topics. I did not see how this might cause the problem, but restored the board to the official release and cleared the cache just to be sure. I received another report after having done this.
***edit***
Just checked my e-mails again. I was wrong. I've not yet had any reports of this problem yet since removing the hack.
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I have a standing request on the board for anyone who might experience this behavior to report it to me. I’ve had none in the last couple days.