http://itsdivinity.com/ looks pretty normal. Apache, etc.
Theme is not the point also - see above, I've installed that 'Custom Community' thingie - works great.
Well, maybe GRA4 conflicts with some caching plugin... In this case try to deactivate everything, install the GRA4, and activate everything back. But honestly I doubt it's a plugin - there is something wrong with the URL...
Weird guess: You are not installing over https, are you ? =)
We probably can assign an engineer for you tomorrow, but you'll have to arrange the access to your hosting somehow, for example: create another admin user, give us id/password, and delete this user after the plugin is installed. It's very unusual error report, so it's interesting to us also =)
Anyways, please be patient. If you want (almost) instant response from the techsupport people (not a gimps from half-sober sleepless developer), at least wait until it's morning on the other side of the water ;)