If the calendar dates are showing up all out of place, then your browser is not using the calendar's stylesheet properly. It may be set up to use a custom stylesheet instead of the one specified by the calendar. Or, it may be Internet Explorer, which doesn't fully support Cascading Stylesheets. In particular, it doesn't support the parts of CSS which this calendar uses. This is true at least of IE for Windows, at least up to version 6.0.2800.1106IC.
But let not your heart be troubled! You can still use the old-style calendar, which contains the same events. It does not contain the nifty mini-month calendars for the previous and next months, but that's the way it goes. (Actually, they will show up in other browsers, but IE can't handle them, so it is told to ignore them.) There is a link between the new-style and old-style calendars at the very bottom of the calendar pages.
If you have been using IE, and would like to see the calendar in its full glory, try downloading Firefox (which is free and works better), or Opera (which is $39 and also works better). Other browsers I have tried also work pretty well, including Konqueror (free) and the Mac OS X's default browser, Safari. By the way, if you switch from IE to one of these, you will notice other nifty things on other pages of this web site that didn't work before.
If you absolutely love IE, and want to remain with it as long as it comes with your computer, then you may do so! I'm not saying all this to criticize IE or your browser tastes. But please, don't expect me to bend over backward to make all the features on this web site work in your particlar browser, when they already work on most others, and already conform to accepted standards.