Mike,
It sounds like a path issue is occurring with the use of the subdomain. I wonder how if it is how the internal workings of power gallery paths resolve.
One thing to try just to check out is if you just installed Power Gallery into a folder on your site rather than creating a subdomain.
So, just make an install point to yoursite.com/powergallery - for example - and then test embedding the ribbons and other assets into your site.
Regards,
Brian