Just to update on this thread - I have been able to make a payment about an hour ago without any complications using google checkout. The google checkout button on the sellers invoice was working as it should.
However, a buyer attempted to make payment earlier this evening using google checkout and from what I've seen, the message I had is the same as everyone elses.
"We've made several unsuccessful attempts to send order notifications to your notification callback URL, https://secure.ebid.net/perl/googlecheckout_in.cgi As a result, you aren't receiving order status, risk or other notifications.
To help you identify the issue with your callback URL, please review the errors we encountered while sending notifications to you. To review this error information:
Sign in to Google Checkout.
Click the Tools tab.
Click Integration Console.
Error messages will appear under 'Integration Issues.' If necessary, you can also update your callback URL in the 'API callback URL' box on the same page."
TBH what with google amending their t&c which I accepted, and then when a buyer attempts to pay by google, google refuse the payment because according to them I hadn't accepted their terms & conditions, this integration problem, and when I attempt to process the payment received tonight, google tell me I have to verify my account - I'm beginning to think that opening the blessed thing 6 or so months ago was not the smartest move I've ever made. In the past 6 months, I've had more problems with google that I've had in the 8 plus years I've had the P*yp*l account.