Just guessing, but your browser is probably an older version of Internet Explorer? You can get the current version by going to Help -> About Internet Explorer (the wording might vary slightly)
If you’re running a version that starts with 7 (or especially if it starts with 6) it would be a great time to upgrade your browser. It’s pretty easy and will help eliminate problems you’ll run in to more and more often around the internet.
You can download Internet Explorer at Microsoft’s site.
Or you can try another browser. Firefox and Chrome are both popular and good browsers that serve the same purpose. Once your current it’s pretty much just personal preference.