Group Management Plugin bugs....?

I asked a queation a couple weeks ago and was told to use Boone Georges' great Group Management plugin. it's great, and I mention some usability issues here, but now I seem to have found some bugs:

I am on the "Options" page for this plugin here:

There are 2 possible settings that can be made:
<Number of members to display per page
Number of groups to display per page>

Regardless of whether I enter a number or nothing, I get the following error message when I "Save Changes".

Not Found
The requested URL /wp-admin/network/options.php was not found on this server.

Is that a bug in the plugin, or something wrong with my setup/system? I am using WP 3.2.1 and BP 1.2.9.

Tks for your help~