No need to click on the ad. Just hover your mouse over it and you should see the url as either a small pop-up or somewhere down near your task bar, depending on what browser you use. Active Low-Carber forum uses *only* Google adsense, so if the url is not from Google, there's a chance you might have some adware or other malware on your computer generating the ads.

Another option is to take a screenshot of the ad, if possible also including the address bar at the top of the page (ie, to show what thread/page you're viewing when you see the ad). Then post it here so we can take a look.

hope that helps,

Doreen