I encountered the same problem. The website I visited that freezes my system was BBC Learning Zone, learning Spanish, also a page with much flash. So, after trying up[censored] drivers, etc., etc. I changed the refresh rate of the monitor and... I just have been 30 minutes learning Spanish on that site.
The right refresh rate for my monitor I found with Everest Home edition (download free from http://www.lavalys.com/).
Hope this is also a good help for you!
NB. I also tried the website you mentioned. I get through. Hope you find a solution.