For months now, I've been grappling with a weird problem: At seemingly random times, Firefox would turn to molasses. I'd click a link and it would take several seconds to register. Or I'd open a dialog box in, say, a blog tool, and again there'd be an unusual delay. Even the simple act of scrolling proved weirdly "sticky."

I was hoping that the recently released Firefox 3.6 update might shake loose whatever detritus was gumming up the works, but, alas, it didn't.

Finally, I discovered the culprit, and it's a head-scratcher: The slow-downs occur only when I've left open a tab containing an embedded video, like of the YouTube variety. When I close said tab, Firefox quickly returns to its quick-stepping self.

Weird, right? Obviously this isn't a widespread problem, otherwise more people would have reported it. I suspect that one of my Firefox extensions (I run about 15 of them) is causing a conflict with Flash, the software that powers most embedded videos.

But that's just a guess on my part. While I'm working to solve the problem for good, my short-term solution is probably pretty obvious: Close any tabs that have embedded videos.

And my lesson for you is this: When weird problems arise, don't overreact. A lot of users would interpret random browser slowdowns as the work of a virus. Or a serious Windows malfunction requiring no less than a system wipe/restore. But glitches like this are par for the course, and with a little patience and methodical troubleshooting, they're almost always curable.

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