Changing font corrupts display

[enhance 0]

My site is working nicely until I change one of the font family settings in Platform Pro 1.5.3 For instance changing the H1 font from Georgia to Arial. Doing this messes up the display totally - all the elements end up all over the place. Only doing a Restore Default settings will cure it, and then I lose all my other settings. Try it yourselves... http://www.canalandrivercruises.com/index.php This happens with all plugins deactivated.

[catrina 103]

Instead of changing the h1 font to arial in the settings, try changing it using CSS to see if there is any difference: [code]body {font-family: arial;}[/code]