Recently installed Cognos 8.2 on one Dev box and 4 prod servers. After installing on each server, I started Cognos Configuration and to my surprise I was unable to see to + or - symbols to drill up or down on the Environment, Security, and Data Access sections. Not only that, I'm unable to modify any group property where I have to select the pencil icon to input values (i.e. Content Manager URI, Dispatcher URIs for Gateway). I'm not sure what the problem could be.
Sounds like you are not an administrator anymore ... There is a SQL script in the schemas directory which adds Everyone back to the System Administrator group. Try it.