Just because your computer came with Internet Explorer, doesn't mean you should use it!
I can't stress enough the importance of a good browser, and most web users are unaware that they have a choice. There's no cost in upgrading to a better program, and it takes only minutes to download.
IE is a stubborn program that refuses to maintain the standards of other browsers. As a result, web pages will often look and act differently with far inferior visuals and performance.
The best web browser for PC users is Mozilla Firefox. Learn about it & download the browser here.
If you feel you absolutely must use IE, at least make sure you have the latest version.
As for Mac users, the best browser out there is Camino. Other browsers include Safari & Mozilla Firefox.