I know this sounds crazy, but bear with me just a second. The problem with Firefox and popups is that it's so good at blocking them! Great at home where I don't use any other browser, but bad at the office.
The office is a nice sensible controlled environment where I can't change the security settings (or just about any settings for that matter) in the IE6 browser. The funny think is that I'm so used to not seeing popups at home, that I often manage to click them at work just because they are convincing and I'm not used to seeing them: like the one that looks like the screensaver setup dialog or a GPF. It's just too easy to click 'ok'.
So my point is that those IE users who get popups all day long do end up far more sensitive than us that use a more securley setup browser.
So the moral of the story: Firefox users: take especial care when using IE at work!