404 on default controller

[eluser]sophistry[/eluser]
are you running multiple apps off one CI codebase?

well, i'm out of ideas... except to tell you to do a clean/new install of CI and see if you can use default route out of the box.

if you can, then there is something wrong with your CI configuration - maybe change the name of the default controller (main is not a reserved word, but maybe too common)?

if you can't get default route to work on fresh install (with your .htaccess in place) then take out .htaccess and see if it works.

if you can't get default route to work at all, then something is wrong with the server configuration and or mod_rewrite.c

cheers.