So it works on your localhost? the problem must be from server config or because you put the silverstripe in a sub folder? did you reinstall (install.php) silversripe on the server.
Yes, it worked on localhost. I reinstalled SS twice on this dev server. This morning I added additional users in phpmyadmin on localhost then exported again to the dev server. It WORKED on login for 1 time. Now it won't allow me access again. This is the same thing that happened yesterday, 1 login and then it wont work.
I used firebug and i saw this error "The website server has not been able to respond to your request" on http://peds.org/_devsite/Security/?executeForm=LoginForm'
These sounds interesting, maybe some of the admin mods on the board can shed some light on this?