Firefox: Curing The CrashFirefox: Curing The Crash

One of the Firefox problems most commonly reported by users is also easily fixable.

It goes like this: Firefox crashes or freezes up. The user shuts it down, and then clicks on the Firefox icon to launch a new browser session. Nothing happens. Repeat until user is fed up.

The solution: Firefox is apparently leaving a process in memory when it shuts down. To solve the problem in Windows, click Ctrl-Alt-Delete to call up the Task Manager. Click the Processes tab. (At this point, it's most convenient to click on the Image Name column header to sort the image names in alphabetical order.) Locate the Firefox process — or processes — and click on it/them, and then click the "End Process" button.

You'll see a warning like this:

Ignore the warning, click OK.

You may have to repeat these steps more than once if you have more than one Firefox process running. Once they've all been killed, you can start Firefox normally.

My colleague Scot Finnie, and most of the users writing in, pointed to the User Agent Switcher as the culprit. This is an extension that allows you to change the way that Firefox identifies itself to Web servers it contacts; the chief purpose is to use Firefox on Web servers that are designed to block access from non-Internet Explorer browsers. Uninstalling the extension will solve the problem for good.

Mitch Wagner is editor of Security Pipeline.