I think one of the page ads is malicious, inappropriate, and dangerous.

I’m not positive my description is 100% accurate, because I was more focused on shutting down Firefox before any damage occurred.

I clicked on an ad at the bottom of a page for (I believe) “Kentucky Candidate john G. Coburn.”

The link tried to download a program called “setup.exe” and linked to URL (I would assume NSFW, also probably harmful for your computer)
http;//porn-x-videos.com/movies/teen/movie1.php?id=1259&bgcolor=000000

The description in the Firefox address bar of the site is “movie.mpg”

(Change the semicolon to a colon to get the link.)

The site had a Flash component that I didn’t see because of Flashblock, but I assume it was a video. And there was a cycle of two or three messages telling me to update Active-X or something. After canceling them, the cycle repeated. At this point, I Ctrl-Alt-Deleted and shut down Firefox.

Here’s a screenshot [100% Safe for work], although Task Manager is covering up the current popup message and most of the Flash component.

Note that these were actual messages from Firefox, not those popup ads that are designed to look like Windows Message boxes.

I think this needs to be looked at immediately.

I am not a computer expert or nothing but it sounds a little more likely that you have some spyware hidden on your computer. Those probably were actual messages from Firefox because whatever site you were being hijacked to simply required a higher level of Flash or something.There’s a helpful thread in GQ explaining steps to take, if that’s the culprit.
If someone has somehow hijacked Google Adsense, I guess you could go to this page:
How do I report a (Google Adsense ad) policy violation?

And if someone actually hacked the SDMB then I guess Tuba or Jerry will see this soon enough. I really think spyware is the best bet, though. I notice that you have a tab for kentucky. com. Did you already have that open or could that be what the google ad was?

I already had kentucky.com open. That’s a legit site. The weirdness happened, totally out of the blue, as soon as I clicked the ad.

I don’t think it was spyware, as I’m clean on Spybot, McAfee, and AdAware. I hope it’s isolated to my computer, but I thought I should report it. So, it’s reported.

What CarnalK says is correct; in the overwhelming majority of cases when someone gets a message like this on the SDMB they have something resident on their computers that gets triggered by the ads. It’s a Firefox message from your machine, it’s nothing on our site.

Spyware gets trickier every day and sometimes stuff sneaks into your system in spite of your best efforts. But it’s not from us.