Firefox cannot find JRE

Although I have Java Runtime Environment (JRE) installed in my computer, every time I visit a website that contains a Java application, Firefox always asks me to install the Java plugin. I follow the steps that given by Firefox, and the installation is a failure at all times. I tried to reinstall the JRE, but the problem still remains.

Luckily, I found a solution in a blog:

1. Go to the Java installation directory, usually it is C:\Program Files\Java\jre1.6.0_05\bin ;
2. Copy all the following files: npj*.dll and npoj*.dll;
3. Paste them into "Firefox installation directory"\plugins\, usually it is C:\Program Files\Mozilla Firefox\plugins.