Opera Woes
Opera users are getting incompatibility errors when loading this site. Which shocked me a bit when I heard. So I downloaded Opera and tried it out, and it works fine, just with the error.
As it should do. Opera is a compliance browser. But, strangely enough it reports "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1) Opera 7.11" that as it's version string. Which annoyingly includes MSIE, triggering the compatibility error, and a 4th Generation browser, and I would say it's a 5th Generation browser.
Anyway, I've included a dirty hack to get around it and Opera users should be just fine. Just need to find a way of convincing Opera developers to use Mozilla/5.0 in their version line.