I am also having this same problem. I have both Authorize.net and Paypal modules installed with my OpenCart server, but neither will go past the "Please Wait" message. As the member above posted, if you click on the button a second time then the page will refresh, but the average shopper may not think to do that. (also, the button becomes disabled, not allowing a second click in IE, but you can click it a 2nd time in Chrome or Firefox).
I have run the transactions in a test mode and can verify that the transactions for both Auth.net and Paypal appear to be completing (confirmation emails sent, orders created in databse, etc), but the checkout page just won't display the confirmation.
I read the two responses in this thread that indicate that a solution exists, but the pasted code didn't work for me, and I was hoping for something a bit more "official" as to a direct, appropriate fix to the problem (since it is supposed to be somewhere in the order.php file, and not the two modules in question).
Thanks, any help would be appreciated.