Gridmarket doesn't show pages for the main site only

Okay...this is weird and I don't know why it's happening.
Gridmarket is the standard theme on my site - I use it on the homepage and for free member accounts. Today I was testing and created a product in a free member account. I noticed that the whole description was showing on the main site (global product list) and changed the option on the main site (In Presentation - Product List Settings) to Show Excerpts -> No.
Immediately pages and posts stopped working on the main site. They are not found (though the title at the top of the browser changes to the correct one for that page). All I see is an "Our Products" page...with no products. It doesn't open the default "store" page as it should.

Any idea why or how that would happen? I'm completely stumped. Everything works fine on the members site. And if I change my theme to something else on the main site...the pages are there and display just fine.
It seems like the free member theme is somehow conflicting with the main site theme.

Any help or suggestions would be appreciated. Thanks!