Upgraded to 3.5.2. Same problem.
As soon as I clicked “Save Settings” in Selective Plugin Loading, I received this error. (Nothing in the error log.)
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Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, webmaster@projectlogin.net and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.
Apache/2.2.22 (Unix) mod_hive/3.6 mod_ssl/2.2.22 OpenSSL/1.0.0-fips mod_bwlimited/1.4 Server at connect.projectlogin.net Port 80
Set WP_DEBUG to true in wp_config.php and see if you can get an error message. Is this a new install or an upgrade of the plugin?
