Default theme not getting set, breaking new signups.

Hello,

My WPMU is not properly setting up the default theme. When I create a new blog the url is broken, only showing a blank file, until I log into the admin panel and pick a new theme. I had the "default theme" plugin installed but deactivated it while testing this issue. Anyone know what might be wrong? The default theme is available and checked as such.

Thanks.

Rich Coy