I've received the following error three times since the forum upgrade (only reporting now that its recurred, didn't note technical support key from earlier instances I'm afraid)...
Error 403
We're sorry, but we could not fulfill your request for /board/index.php?action=post2;start=0;board=2 on this server.
You do not have permission to access this server. Before trying again, close your browser, run anti-virus and anti-spyware software and remove any viruses and spyware from your computer.
Your technical support key is: 91ff-f00b-b40c-8ddc
You can use this key to fix this problem yourself.
If you are unable to fix the problem yourself, please contact the WEBMA5TER and be sure to provide the technical support key shown above.
It arose when quoting someone else and attempting to include a URL within the markup. Tried again and it worked fine.