At some point in the last half hour, my Firefox window disappeared. I didn't notice, as I was working in another program at the time. No Firefox icon shows up with Alt-Tab, and no Firefox listing shows up under the Applications tab in the Task Manager. There is a Firefox entry under the Processes tab. Normally, I probably wouldn't have noticed, and would just open Firefox up again, but I'm listening to an Internet radio station and the stream never stopped.
When I did open a new Firefox window, it showed up in the Task Manager's applications tab. I'm running Windows XP, and my Firefox has the add-ons Adblock Plus, BetterPrivacy, Cert Viewer Plus, DOM Inspector, Firebug, Greasemonkey, Java Quick Starter, Live HTTP headers, Microsoft .NET Framework Assistant, NoScript, WebDeveloper and XPather. The radio station is Slacker; it's never given me any trouble before, and I've been using it for months. I don't think there was anything unusual in my open tabs; just a few static pages at non-sketchy sites like Java APIs, plus GMail and the aforementioned Slacker.
Searching Google brought up a handful of similar-but-not-quite-the-same errors, none of which had useful resolutions. Does anyone know how to bring that window back and/or prevent this from happening again?