So I recently added a second "dev" wordpress installation, so that I can edit my site without the changes going live. So i changed the table prefix in my wp-config.php, installed a second copy of WP to http://www.domain.com/dev.
My original "blog" install is set to load from the root domain, so when you visit http://www.domain.com, you see my site.
Now I'm able to access my dev install, but when I try to log into my blog install at domain.com/dev/wp-login.php, I get told to "please log in again" and I get redirected to http://www.domain.com/dev/wp-login.php?redirect_to=%2Fblog%2Fwp-admin%2F
From there it wants to log into the dev install, but if I try, I get a redirect loop.
What did I break?