I also had this problem with an x201s. The display on the laptop alone was fine, but on attempting to plug in an external display, both displays go black. I downgraded my linux kernel from 2.6.38-9 to 2.6.35-22-generic from the maverick repositories and this seems to have fixed the problem.
I also had this problem with an x201s. The display on the laptop alone was fine, but on attempting to plug in an external display, both displays go black. I downgraded my linux kernel from 2.6.38-9 to 2.6.35-22-generic from the maverick repositories and this seems to have fixed the problem.