This one is really messing with my head.
Take a look at: http://d413049.he73.hostingessentials.co.uk/
In firefox the last menu item "Contact us" displays no problem, but in safari, ie, opera or chome the menu item is missing. Furthermore, the <li> is actually missing from the HTML source when you view it?!
How can SS deliver different mark-up to different browsers when viewing the same page? Madness!