Dan,
Thanks for the admin access. That helped narrow things down. The issue is that the review popup is trying to add that modal background, but is not applying any styles to it. When that happens, the JFBConnect styles kick in, and for some reason, cause that wackiness.
If you can add the style below to your template's CSS file, it will force the modal backdrop back 'farther' behind content:
.modal-backdrop {
z-index: -1;
}
It still may not be the effect you're looking for.. in which case we can help you undo the backdrop greying out altogether.
Let me know how that goes, and sorry for the troubles.
Alex