There is a problem when saving the ACL.
You can easily reproduce it following these steps:
1. Open ACL page in administration
2. Check "Admin area. Manage plugins" for the Vendors role.
3. Click "Save"
4. After the page is saved, click "Save" again or enable another permission per role and click "Save"
You should get this error:
SqlException: Violation of PRIMARY KEY constraint 'PK_PermissionRecord_Role_Mapping'. Cannot insert duplicate key in object 'dbo.PermissionRecord_Role_Mapping'. The duplicate key value is (40, 5). The statement has been terminated.