Not on the test server. I log in at home and at work. I visit the site randomly a few times a day. About half of the time I visit, I get the popup. I'm using Firefox on Windows and Mac OS X.
I think I know how to pseudo fix this. Here's the deal: with the way sessions are dealt with, you can only be logged in on one computer at the moment. I'm gonna inquire with our coder guy as to how easy / hard it would be to fix this, but we're kinda tapped out financially at the moment so if it's more than a one hour fix, the best I'll be able to offer for the next little while anyways is that the system will simply auto-log you out rather than annoy you until you manually log out.