Can't progress through the checkout process

[christianb2]

I created a customized shipping module that was working fine and now for some reason it doesn't allow me to get through the checkout process. It displays the first page, the Delivery Information page, with no problems but when I click on the Continue button, the screen is just refreshed and I'm back at the same page. It doesn't progress to the Delivery Information page. I know the shipping module is the culprit because if I disable it and enable another module, checkout works fine. I know this is a hard one to diagnose without seeing my customized code, but can anybody out there point me in a few directions? I have looked at the database for corruption or artifact records left over from my customization work, but everything looks clean. Any thoughts?

[doug]

I had a similar symptom however not because of a Mod, problem was the product(s) I had in my cart had a weight in the database of 0, I changed every product to have a non-zero weight and it worked!