apache error_log:
[Wed Sep 20 15:09:09 2006] [error] [client IP] (20014)Internal error: Can't open file '/usr/local/svn/guide/guide/format': No such file or directory
[Wed Sep 20 15:09:09 2006] [error] [client IP] Could not fetch resource information.[500, #0]
[Wed Sep 20 15:09:09 2006] [error] [client IP] Could not open the requested SVN filesystem  [500, #2]
[Wed Sep 20 15:09:09 2006] [error] [client IP] Could not open the requested SVN filesystem  [500, #2]
 
I know there is no such file, but there is not supposed to be.  webdav should redirect, according to svn documentation, through the httpd.conf excerpt below.  I've confirmed compilation and existence of all modules, and all files exist and are syntactically correct.
 
<Location /svn>
  DAV svn
  SVNParentPath /usr/local/svn/guide
  AuthzSVNAccessFile /etc/authz-svn-access
  Satisfy Any
  Require valid-user
  AuthType Basic
  AuthName "Subversion Repository"
  AuthUserFile /etc/svn-atuh-file
</Location>