Http:// and Https:// pages in Marketpress are conflicting

Hey everyone,

I'm looking to see if anyone else has experienced this or can point me in the right direction to fix it.

I'm currently using Marketpress on my multisite that has a main site and one subdomain. I have a UCC certificate that allows for both of those to be secure. The problem is that the https is causing some problems with my store pages. I'm able to get to the products and add them to my cart, but not much after that. I can't update the quantity in my cart, remove any items or get past the shipping info page. After I put my shipping info in and hit next, it just reloads the same page without any information in the fields.

I know this has something to do with my UCC certificate, I'm just not sure how to go about fixing it. The pages within Marketpress are producing 404 errors. I tried contacting my house, but they were not helpful.

I'm also currently using the plugin WordPress HTTPS to force the SSL on my pages. Below are some screen shots of what's happening when I try to make any changes within my cart.

Thanks in advance for any suggestions!