4.08 or higher or Internet Explorer version 4.72 or higher.
Most people report that their problems disappear when they use a recently released browser.
The site is perpetually under construction, so you will find that many sections do not yet have explanatory text or audio clips. Most of the animations are complete, but not all. The text, audio, and will be animations should be completed during the summer of 1999. The links use JavaScript, so you need a browser with this capability. For some reason, Netscape versions prior to Navigator 4.08 won't execute these simple scripts properly.