When I open web pages that use jar files in applets, all I get is a blank black rectangle where the applet is supposed to run. This is a typical line from the source code of one such web page, which I am using to learn Java and contains a code example: It is taken from the following web page of just one of the various sites that I have been usint: http://math.hws.edu/javanotes/c6/s3.html As far as I can see I have all the necessary plugins for Firefox, including: Java Deployment Toolkit 6.0.200.2 Java Platform SE 6 U20 Java Console 6.0.20 I am running Firefox 3.6.3 under Windows Vista Home Premium SP2. Looking at Firefox Help, there don't seem to be any settings that I have missed. Any thoughts? It's probably something obvious that I have missed. == URL of affected sites == http://math.hws.edu/javanotes/