Unwanted thread subscriptions

Recently, I noticed that some threads I’ve posted to have appeared in my User CP as subscribed threads. Luckily for me and my email account, the “no notification” option is active, but – why would this be happening? I don’t click on any “subscribe to this thread” I can see, and it doesn’t happen with every thread. Right now, every so often, when I see the “subscribed” icon turn up on the screen, I just go empty 'em out of the CP.

I’m using Firefox 0.9.3.

Go here and make sure the “Default Thread Subscription Mode” pulldown menu is set to “Do not subscribe”

Just checked. It already is. I’ve never wanted subscriptions to threads.