1) /admin/plugins/projects/index.php is missing an include for lib-common.php
Opps ok will add that line
2) After fixing that, attempting to view the index page results in a SQL error. In particular it appears that 'gl_projects.last_release' is an unknown field in the table. Sure enough, a quick peek into mysql shows that there is no such field.
The field should be 'gl_projects.proj_lastrelease' If its missing you may have used the RC3 installer which was not adding that field by accident, there is a file gl_projects_1.0RC2_to_1.0rc3.php in the admin fodler that will add the homepage, downloads and proj_lastrelease fields to the database. Else download RC4. Its thats what you have then some diggin on my part is needed to see what missing.