Cross-platform issue

Hi,

I’ve a photo gallery with a navigation panel made of little buttons with numbers which, after clicking on them, load the relative photo on the right hand side.

This is the page: w w w.newtreedesign.co.uk/test/douglas/_test.html

When a number from the navigation panel is clicked, it should turn purple.

It all works fine in safari/mac latest versions but there are problems under IE/Win and FireFox/Win, the other 2 environments I’m keen to have compatibility.

Could please anyone suggest me what corrections I’ve to make on the code in order to be sure I’ve this compatibility issues sorted?

Thank you
paquito