Ok, I'm working on it. I'm pretty sure that it's the "Clear" ad (see attachment) and am working with the ad companies to try and get it blocked.
Anyone that has noticed the error in the lower left of IE (shows as yellow warning with an !), can you confirm that this add (might look slightly different, but some variation of "Clear security") is on the page. If not, let me know what adds are showing, in case any others are causing the error.
I'm not 100% this is also what's causing the crashes. I'm "hoping" that it is the same ad.