Stumbled on this post, I had the same problem. That did the trick for me. Thank you @davidosullivan !!!
For future reference for anyone else, the errors were:
Warning: in_array() [function.in-array]: Wrong datatype for second argument in /path/to/domain/wp-content/plugins/capability-manager-enhanced/includes/network.php on line 58
Warning: array_diff() [function.array-diff]: Argument #1 is not an array in /path/to/domain/wp-content/plugins/capability-manager-enhanced/includes/network.php on line 62
Warning: Cannot modify header information – headers already sent by (output started at /path/to/domain/wp-content/plugins/capability-manager-enhanced/includes/network.php:58) in /path/to/domain/wp-includes/pluggable.php on line 1121
