DVD won’t play when laptop “undocked”

I have a Lenovo T60p laptop with Matsushita DVD-RAM UJ-842. When docked in its docking station it will play a DVD on either of two monitors I have connected (The laptop’s and an external). I can uncdock the laptop and it will continue to play the DVD. If I try to start a DVD while undocked, I get an on screen message “Create overlay failed, please lower screen resolution or color depth and try again” This is when playing with Intervideo WinDVD. It is the same for Windows Media Player except I get audio only when starting the DVD undocked.