PROBLEM: When setting up a new account in WLW Beta 3 for a Wordpress 2.2 blog, the following error is returned:
Invalid Server Response - The response to the blogger.getUsersBlog method received from the weblog server was invalid. / Invalid response document returned from XmlRpc server
CAUSE: A file loaded in xmlrpc.php is unable to be found because of invalid path information. Line 18 of this file contains the following statement:
include('./wp-config.php');
This will cause PHP to search its path for this file rather than loading it directly from the current directory.
RESOLUTION: Alter the above statement to read
include('wp-config.php');
Note that there are other possible causes for this error; the above is the one that has worked for me.