In Safari 5.1.2 on OSX is totally damaged.

Many people pointed out an additional div tag being the reason, but that also did not fix the problem.

Any help could be greatly appreciated!

Pretty fundamental: fix your xhtml errors [Invalid] Markup Validation of - W3C Markup Validator (scroll lower within the validation are accountable to see line amounts and source code). And employ Firebug with Opera, or perhaps in Chrome or Safari or IE8, make use of the developer tools to locate and connect the javascript errors.