PHP Errors

First of all, how is it I never knew about punBB before??  What a great forum app!  It is simple, easy to configure, easily integrates into my current site and the xhtml/css code actually validates!

I'm working on getting it set up on my site an I'm running into a problem.  I've added Apache includes in my .tpl files to pull in the formatting code from my cms app in another directory. Usually this works fine but on an occasional screen I get PHP errors.  As far as I can tell it's always when the admin user is logged in, and not when other users are logged in. It happens on the admin options screen and on an occasional post, but not all of them.  The errors I'm getting are:

PHP Warning:  require_once(./include/config.php) [<a href='function.require-once'>function.require-once</a>]: failed to open stream: No such file or directory

PHP Fatal error:  require_once() [<a href='function.require'>function.require</a>]: Failed opening required './include/config.php'

PHP Fatal error:  Cannot redeclare myaddslashes() (previously declared

Suddenly it just can't find the config.php file for my cms and it's unable to pull in the layout.  Just bare punBB.  I realize that's probably not enough info to trouble shoot my problem but I'm just wondering if anything in those error messages rings a bell with anybody.  If so it may give me a clue as to where to look further.  Any help would be much appreciated.