if the screen goes red during loading then there was a problem loading the file.
Most likley the file does not exist (try the java console in your browser it will give more details)
if the screen goes black and red then you may have an out of date Java VM.
http://www.microsoft.com/java and get a new one.
if you get nothing make sure java is enabled.
if the buttons do not work, make sure javascript is enabled.
more info at http://www.jumpstation.co.uk/jvmu