With Nuke 6.0 you do not have to CHMOD the config.php file 666. It writes the preferences to the databse in Nuke6.0 not the config file like it did in earlier versions.

Not sure why you cannot change preferences. Have you changed to a NON-Default Nuke theme?
That may be the problem. IF the theme is not specified for Nuke 6.0 then form type submission links can malfunction. Can you change anything else, LIke Vote on a survey, or do anything else that requires clikcing a SUBMIT button?

mikem