
If your computer has more than one browser ( like Internet Explorer, Chrome, Firefox and Opera), you may find it difficult to set the default browser. However some web browser have the “Set as default browser” feature, but that often can not completely solve this problem.
Also see: A Brief History of Web Browser Usage
Here is a software is designed to deal with this situation, it can easily reset all related settings and help you solve this problem.
Change Default browser is a small utility for windows to change the default with a click without performing any individual browser settings. When the program starts, It automatically determines the web browsers installed, if not, you can browse them manually. Now select the browser name which you want to make as default and click Set Default Browser.

Also see: Google’s Web Book – “20 Things I Learned About Browsers and the Web”
It is absolutely free and works on Windows XP, Vista, Windows 7 and Server 2008.