Hmmm

My htaccess file has been renamed to htaccess_causes_conflict - datestamp corresponds to the date of the cloud migration.

contents of this file look like this...
RewriteEngine on
RewriteCond %{HTTP_HOST} ^forums.hcmaces.com$ [OR]
RewriteCond %{HTTP_HOST} ^www.forums.hcmaces.com$
RewriteRule ^.*$ "http\:\/\/www\.hcmaces\.com\/forums\/ubbthreads7" [R=301,L]

I guess this could be a red herring as it dates back to when i originally hung the forums from a sub-domain (which has not been the case for a long time).