It took a few hours before my anti-virus software would let me visit the forum as it reported that the site was attempting to download a hostile program, I suspect it's the ad carousel, do pro-boards check this? AV seems happy now (obviously)
You've probably forgotten all about this now, but I checked into it with Proboards and there should be no issues anymore. They said they do check the ads, but it's possible one could have slipped through. Sorry for the late reply, I haven't been on the forum since February so I never got the chance to check into it until now.