I am using the Community Edition, version 5.2.0j and I ran into a peculiar error I hope someone can point me in the right direction to resolve.
I created a custom relationship for project tasks (many-to-many) to point to projects. The goal was to have common project tasks visible from more than one project. During the relationship creation I filled in what was editable. I get the default sub-panels. All seems to be functioning fine, except I get a warning message at the bottom of the screen:

Warning: aSubPanel::include_once() [function.include]: Failed opening '' for inclusion (include_path='/var/www/SugarCE-Full-5.2.0h/include/..:.:/usr/share/php:/usr/share/pear') in /var/www/SugarCE-Full-5.2.0h/include/SubPanel/SubPanelDefinitions.php on line 316

Fatal error: Class name must be a valid object or a string in /var/www/SugarCE-Full-5.2.0h/include/SubPanel/SubPanelDefinitions.php on line 317

Any idea what is causing it and how can I fix it?

Thanks,

P.