Some problems with Java are caused by settings in the browser preferences. If you are having problems getting Java based experiments and demonstrations on IPL to work, check the browser preferences for your browser type below.
At the top of the browser window select "VIEW" menu -->"INTERNET OPTIONS" -->"ADVANCED". Make sure that "JIT COMPILER FOR VIRTUAL MACHINE ENABLED" is checked. Click "APPLY" to set changes. You will have to re-start your computer.
If you are still having problems with Java based experiments on IPL, review the information on your specific browser.