After activating a plugin every page, user and admin, displays the content 'Not found' and the URL is always sitename.com/null All the sidebars,header and footer are displayed correctly. Visting any page/link re-directs back to /null
Deactivating the plugin restores normal operation.
The plugin in question is, http://wordpress.org/extend/plugins/motor-racing-league/
I am the author of the plugin and have determined, with help from the user, that after changing to the default theme my plugin activates and the site works OK.
I have installed the atahualpa theme, same version 3.4.2 and all the users other plugins on my test server and do not have a problem. I haven't applied all the same theme/plugin settings are there are so many.
I have spent hours and hours trying to fix this, and I'm not blaming this theme, I would just like to find out why this is happening.
Any help would be appreciated, as this user, who has donated to alahulpa, would like to use my plugin and and I would like to ensure that other users do not have a problem.