Occasionally, I've been "logged out" from MO briefly for no reason I can see. I use quotes because although I get the "First time user?" orange bar at the top of the screen, as soon as I load any new page (such as by clicking on a question) everything is back to normal. Today something even stranger happened--my user information at the top of the screen changed to that of JS Milne! But again only a single page load was affected.

This doesn't seem to be causing any actual problems, but it is somewhat disconcerting...

I think I have found a way to make this bug repeatable. Whenever I go to http://mathoverflow.net/jsMath, I find my name displayed as José Figueroa-O'Farrill. This occurs whether or not I am logged in, and survives clearing my cache. Going to anoter page undoes the effect.

I visited that page many times, and got strange results on three occasions--"Anton Geraschenko", logged out, "Shake Baby"--but mostly "Reid Barton". Then I tried loading the page from another browser where I was *not* logged in, and got "Reid Barton"... I suspect somewhere the page is getting cached too aggressively, either on the server itself, or by a "transparent proxy".