Did you change much in the CSS files? Unfortunately IE on a Mac is broken; I faced the same problem (IE crashed) with positioning elements in our CSS files. Had to make a check on the browser to feed a much more simple style sheet relying on the original css with ezpublish 3.4.
Thanks for your comments Paul. Mark also agreed that CSS is the likely culprit, so I'll have a dig around and see if I can find the elemtn causing the issue :)
Also I posted a problem with floating images. When you float an image in IE mac you need to specify both height and width of the floated object. You can look up my post on how i modified the template for this. Anyway it is very easy to make your site 100% mac compliant.