Hope this hasn't been posted before, wouldn't be sure what pharse to search for, but moving on...
http://www.digitalhomecanada.com/
This site has found a way that FF + AdBlock Plus users can be denied viewing the website. You have to turn off AdBlock Plus or added to whitelisted sites.
Using AdBlock Plus denied entry to website.
A seach on these forums for digitalhomecanada brings up. These results. Not trying to be mean. Just pointing it out for future help. Also it doesn't work if you disable javascript on that site. Or it doesn't for me anyway. I use noscript extension and it doesn't allow javascript on a site until I allow that site to run javascript (btw, it's not the same as Java)