404 error for just one edit window
If you remove the redirection rules you have to set $wgServer back to the original non-redirected folder.
Ok that broke the skin or something, the text was present but the site elements weren't, and the 404 error was still there.
To be specific, there's a problem on that page that's causing an incorrect redirect to an unauthorized location (a 403, not a 404, error). I think a developer should comment here.
I was just fiddling around with the redirection settings and it started eating my localsettings.php, each time I saved it, more of the text vanished. I restored everything from a backup (except for some settings that disappeared) but it was weird. Is it to soon to comsider that mediawiki has gained consciousness and is trying to censor anti-gay rhetoric? There are worse scenarios for software gaining consciousness...
Damnit, I don't know why I ever try to fix anything on my own, I always just end up making it worse. My custom namespaces are gone, and I recreated them but the pages that were there are gone now... I've got a buttload of content to recreate now.
Eating your LocalSettings.php?? Something's wrong with your website security then.