Okay, working now, though I didn’t change anything.
For anyone who may encounter this in the future, the problem I was facing was actually a problem with the fonts loading; the resources requested from themes.googleusercontent.com/static/fonts/* were not loading, which I assume is why all of the overlays (which use those fonts) were not behaving properly. Just a guess, anyway.
I am having the same problem with Firefox 17.0.1 on OSX and Safari 6.0.2.
In addition to not having any of the sliders loading (only getting the loading circle) on the homepage and my subpages (e.g. portfolio), I also am not getting a mouseover effect on any of the post images, and they are also not linked. This means, for example, that any portfolio links from thumbnails, be they in the portfolio gallery or in the homepage “latest projects” block do not exist. The image is there, but no link and no mouseover.