Justin

It’s a shared hosting environment so I don’t have ultimate control. However as far as I’m aware the oauth PECL extension isn’t installed.

Upgraded to PHP 5.5 and plugin activated successfully.

I’ve tested this by deactivating all plugins and reverting to the standard 2012 theme – still having the same problem with the same error.

I’ve been able to reproduce this several times, and the error always seem to be the same:
[error] [client XX.XX.XX.XX:52426] AH01215: PHP Fatal error: Cannot redeclare class OAuthException in /XXX/public_html/wp-content/plugins/keyring/includes/oauth-php/OAuth.php on line 8

I’m on PHP 5.3, but unfortunately I’ve not yet establish where the conflict is coming from. More testing required.