Role Scoper cannot operate because another plugin or theme has already declared the function "set_current_user" or forced early execution of "pluggable.php". All posts, pages and links are currently hidden. Please remove the offending plugin, or deactivate Role Scoper to revert to blog-wide Wordpress roles.

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The function "set_current_user" is handled by WordPress as a pluggable function. This aspect of the WordPress API allows a plugin or theme to override certain core functions. I'll not take the time now to describe why it's necessary in this case, but rest assured this is not due to a misnamed function.

The Maintenance Mode conflict is longstanding and documented. If the directions there do not resolve your conflict, there is probably an equivalent plugin which does not conflict with Role Scoper.