I have just set up a UD-3900 with my Lenovo Thinkpad to work over two screens. Everything went very smoothly until the screen turned itself off for the first time. Upon waking the computer up the screen connected by HDMI continually flickers. The only way I have worked out to stop this is by removing the power cable from the plugable and then plugging it back in, at which point normal service resumes.
I am using a VGA to HDMI adapter as well for this screen.
Thanks,