Just tested this plugin on clean twenty twelve install, s2member PRO version.
First, when activate, a notice (yellow default) says unexpected characters sent in headers ...
Propably not enclosing ?> php tags in the end of your files. OR ?
However, the big problem is BOROWSER -> Managing files
A spinner shows up, and then the page dies blank. My script debub reports jQuery not defined, and then som undefined variables as a part of the first error issue.
In the sourcecode, the jQuery ui is loaded.