Until this morning, my Lenovo Thinkpad T430 running KDE on Fedora 19 was working fine sitting on a base with a second monitor attached. I removed it from the base and connected another second monitor (a projector) and things were still fine. When I put it back into the base, the laptop screen went blank, and it was using only the second screen. When I remove it from the base, it uses the built-in screen, but as soon as I put it into the base, it only uses the second screen. Interestingly, when I restart, it uses both screens properly until after I log in.