works fine for me;
either your browser isn't compatible (I've got windows 7 /IE8 on my netbook, not tried it on my XP machine), you are getting the wrong numbers...? - or perhaps you are not doing it quite right (instructions are sparse...); in case it is the latter try this.
1) select a hub, e.g. press 'campagnolo' button, then select chosen hubset, (e.g. 1999+ Athena front) -highlights in blue.
2) select a rim, e.g. search 'Mavic', select (say) A119 (307ERD) -highlights in blue.
3) select drillings e.g. 32 -highlights in blue
4) select crossings e.g. x3 -highlights in blue
bingo- 297.4mm
You can add decimal crossing values, and decimal spoke numbers; these are mad for 'normal' wheels, but essential for weird spoking patterns. You can also add your own values instead of using the drop-down lists.
Obviously anyone can add data, so some of it may be duff; hence it is good to do a sanity check on the values, which are quite visible.
If there is a fundamental problem, you can feedback via the site, I think via a link on this page;
http://edd.uservoice.com/forums/26386-generalanyone else having problems?
cheers