I have a Macbook Pro (13 inch) running Mountain Lion. Suddenly, for no reason I can figure out, when I go to Twitter using Safari, the Twitter site reverts to the mobile version of the site. This just started happening in the last day or two. I am wondering if anyone else has experienced this issue and if you know a fix? I don't know if this is a Twitter site issue or some setting in Safari? WHen I use Opera, this problem does not occur.