The first question in these cases is - which browser are you using?
Some browsers that have problems with this site are Internet Explorer and Opera.
Usually Firefox 3 is the best bet, no matter what system you're using (unless you have Mac. I understand Safari works fine. Also Google Chrome works well.)
Several people, including myself, have noticed that the analysis board is not working. It opens, but it is just a blank board with no pieces. The movelist is visible, but clicking on any of the moves doesn't have any effect either.
[Just noticed that there is a support forum - this probably should have been posted there instead of here]