Yep IE done the same for me, I installed an earlier version and that seemed to fix it. I prefer Firefox, always have but it's noce to have a back up.
Tho my advice to you would be, get rid of the beta version of Firefox, it is riddledwith problems I've been using it since they launched it, it crashes probably 3 or 4 times a day. It started off fine but think it picked up some compatability issues as windows updates where downloaded!!! Use the normal version until it's no longer a beta. I run a beta machine, most of my software is beta yet I'm still avoiding Firefox beta!!