Open one of the html files in a web browser. Did the Physlet run properly? If yes then great! You can ignore the rest of these instructions. If not then you probably need to update either your web browser or your VM. See the next step.
You must have a virtual machine installed and running on your computer. If you are using Internet Explorer click on "tools" then "internet options" and then on the "advanced" tab. Scroll down to where you see "Microsoft VM". At this point you will see something like what is below.
In order for the VM to be running there must be a check beside the "Java console enabled". If it is not checked, check it, apply settings and then restart your browser. Hopefully this will have solved the problem
Some versions Windows XP and some versions of IE 6 were not shipped with a VM. If you do not have the VM option you will need to to to Microsoft and download a VM
Notice that there is a Java icon just above the Microsoft VM icon. You will see this if you have the Sun VM installed on your computer. You can run Physlets with either the Sun or Microsoft VM so if you prefer, uncheck the Microsoft VM and check the Sun VM.
If you are using Netscape you will need to go to the Sun website and download Java Runtime. Once the Sun VM is installed Physlets should work
If you have a Mac you must be running OS X in order for Physlets to run. They do not run under OS 9.