The preview works correctly except that the intro screen is never displayed during preview and occasionally is swapped with the ending screen, however, the main issue happens when you press "Play" and the slideshow appears on the selected monitor, it stays there after any interruption of the show and even upon completion.
Changing modules does not clear the display. Only exiting Lightroom.
Also, if you stop the show, make a change and start it again, there is occasionally a dialog box that is displayed behind LR which requires the program to be stopped through the Windows Task Manager because LR is waiting for the modal dialog to be satisfied.
I am running an ATI Radeon 6800 HD (2GB) PCI-E Display Adapter with the latest drivers on Windows 7 Premium with the latest service packs and all updates on a Quad Core AMD FX PC with 16GB RAM.