In accessing Groupon, after going to various links, the site morphs into either Russian or Chinese language from English. What's happening and how do I prevent

When I access Groupon, I can browse the site for several minutes, but then the site changes to either Russian or Chinese characters and I cannot read anything again, even if I log off and log back in. It occurs whether I initially log into the site or not. I did grant a security exception, but cannot find anything that tells me how I can revoke it to see if it's the problem.