That's the exact same page...
No it isn't.
It is either your chrome-installation that is causing the problem or some url-hijacking malware. I can access the forum just fine with all three browsers I have installed, there's no such ad at all on the page.
There has been a security issue with a couple of addons to chrome very recently. It's likely one of your addons doing that. Deactivate them one by one to see which one is the culprit and then throw it out. Once you found it, file a complaint with google, to have it taken out of the store.
The attack works like this: Some ad-distributer buys the addon from the developer, writes some adware in it, chrome updates the addon. Same attack is used with firefox-addons lately. The addons did not get verified before every update until now, which is likely to change and make things more complicated. All because of some #!*?&§$##1!!1. I start to consider to turn back to w3m. grumbl
Or you could backup your bookmarks, uninstall chrome completly, run ccleaner, spambot S&D, and some antivirus of your choice, reininstall chrome, try with a barebones naked chrome.