Hmmm... it's being weird.
Now, UPS Ground shows up when you are first in the cart, but as soon as you click on "Calculate Shipping", the shipping methods disappear and it gives the error. Freaky.
I will have to look at the tables, and make sure that no products have product level shipping defined.
I have verified that in the cart setup that "Cart Shipping Calculator" is checked, and that in the store admin menu, under "Shipping", that nothing is defined in any of the buttons in there.
I'm looking at the tables now to see what I messed up.