Steps to reproduce:
I installed the plugin on a 3.0 RC1 blog, using a Twenty Ten child theme. I activated the plugin, and then edited a page (to assign a member of type "author" to be able to edit the page). I then logged out of the Admin account, and logged in as the member with the new capability. I then clicked to go view the blog (see the main page). The first time I tried to view the blog, the main menu (a Twenty Ten theme feature) had the following error messages within the menu itself:
Warning: preg_split() expects parameter 2 to be string, array given in ~PATH~/wp-content/plugins/role-scoper/hardway/hardway-taxonomy_rs.php on line 235
Warning: Invalid argument supplied for foreach() in ~PATH~/wp-content/plugins/role-scoper/hardway/hardway-taxonomy_rs.php on line 237
Afterward, I clicked through several pages, but did not see the error messages any more. I edited the page as the member with the new capability, and still saw no errors. I then logged out and browsed the site. No errors. I logged in as Admin, and browsed. No errors.
Any ideas? At this point all seems fine, but I did see those errors right out of the shoot. ??