Javascript problem in IE 7.0.6

Hi

The website http://stompfrog.co.uk/ works by the navigation scrolling to a particular content section using some javascript.
This works fine in firefox and my version of IE however in IE 7.0.6 you need to click the links a couple of times for the javascript to navigate to the correct page, what could a possible reason of this be?

Thanks

I just tried in IE 7.0.6001.18000 and encountered no such problem.

It is strange because it only seems to happen on one particular laptop, I could not think what else could cause it other than browser compatibility issues though?