Some redirect issues.... I think!

Hi all -
just bought the plug-in and setting up a simple purchase on our site.
Everything seems to work - until, I click add to cart. There's some sort of re-redirect issue.
Our site is set to redirect to the WP install folder. Any page, product, image, etc., works just fine.
But the add to cart is problematic.
Site is http://www.ablangallery.com
Add to cart goes here:
https://www.ablangallery.com/~ablangal/~ablangal/2011/store/shopping-cart/shipping/

Have no idea why or how to fix.

Thanks for any info
Dan