[SOLVED] see here
I have noticed, that some pages begin with "www.physicsoverflow.org/..." whereas some begin with "physicsoverflow.org/...", i.e. without the www.
This does not seem like a great problem at first glance, at least it didn't to me, but now I realise that there is a huge danger in this.
First of all, this means, that when I login on a page whose URL begins with www.physicsoverflow.org, I am not automatically logged on to a page whose URL does just begin with physicsoverflow.org. (I have observed this, and the only explanation I can give is this) Still not a big issue.
Now, the big issue, which I have not observed yet, though, is that if you are logged in to both www.physicsoverflow.org, and physicsoverflow.org, logging out of either one does not log you out of the other. Now, this, is obviously dangerous, because few people will notice this issue, and this could end up being a problem on public computers...
So, this isn't exactly a "minor" bug (I'm changing the title of this question).
Update: It has now been observed that as I predicted, the same behaviour does happen with logging out. Logging out of physicsoverflow.org doesn't log you out of www.physicsoverflow.org