Thanks for taking the time to thorough respond to my post. I am sorry I didn't explicitly state that this problem ONLY occurs with orders that are paid for FULLY using a gift certificate. All other edits work just fine as well as accessing invoices, packing slip and such. We currently do not have any mod that affects the checkout flow. We used to have Rewards Points and Google Checkout Mod but those are no longer on our site but still have their tables and configurations intact in the database.

The host are claiming that they are not seeing anything more. We are on a dedicated server and I have root access and I did check all the logs out there and I don't see anything myself that is useful (at the moment). Still digging.

I know there's a tool (or code) I can use to printing what's happening but I don't remember how to implement this at the moment. I am basically hoping there's some debugging/sniffer I can activate.

Again, thanks for your help.