Please try the following things:
1: Check the error logging and display settings in the php.ini file, make sure the error log setting is on, and check the error logs on your server – if any are there (related to the include plugin) please send them to me
2: Re-name the plugin folder to something else, load the wordpress admin, then change it back, and try again
3: Go into PhpMyAdmin and try to run a repair on the wp_options table
4: If you have WP SuperCache, try disabling it, and then try activating Include again
If that doesn’t work, for the sake of narrowing it down, please setup a fresh wordpress install in a subdirectory ( pointing at a different database ) and try installing JUST the include plugin.
If it activates on the fresh install, then there’s a conflict between include and another plugin on your site; and I’ll need a list of all of the plugins you have installed.
If it still won’t activate on a fresh install; I’m going to need the following information about your current server setup so I can attempt to test this:
* WordPress Version
* Operating System and Version
* PHP Version
* MySQL Version
