Just found more information.
When Multipress is activated and you go to the url: http://xxx.com/xmlrpc.php, you get the following messages:
Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, ‘multipressContent_xmlrpc’ was given in /home/xxx/public_html/wp-includes/plugin.php on line 166
Warning: Cannot modify header information – headers already sent by (output started at /home/xxx/public_html/wp-includes/plugin.php:166) in /home/xxx/public_html/wp-includes/class-IXR.php on line 311
XML-RPC server accepts POST requests only.
If Multipress is deactivated you will get this:
XML-RPC server accepts POST requests only.
I love the way the plugin works, but would also like to keep the XML-RPC updates I get from other sources.
Thanks!