Checkout button just returns to cart page
 

When clicking the checkout button from the main page, or from within the cart (whether customer is logged in or not), the user is returned to the shopping cart... When any "chekout" button is clicked (cart.php?mode=checkout) the browser url displays a few diff locations before returning to the cart. Also, the background color is set to default for a few seconds (white) which never happened before and doesn't happen when moving between any other pages.

I can't find any threads about this so I guess I'll assume that I accidentally broke something but I don't know where to go to start looking for the problem.

Here's the shopkey so anybody who want's to try it themselves can. http://www.madragz.com/store/home.php?shopkey=tequilaboy180x

Yep, something is definitely up. Have you messed with cart.php or cookies?

EDIT: My mistake. We didn't touch cart.php, mostly changed /skin1/customer/main.tpl along with a few other tpl files here and there.

I would start by putting back the original cart.php and see if it helps. Then you can start adding the mods back in piece by piece until you see what is causing the issue.

Figured it out.
Turns out there was no https module installed on the new server but somehow the modifications to the site prevented an error message from showing up.
Added libcurl php extensions (windows box) and everything works fine now.