That's caused by DBPro having to loose all the media - so when you alt+tab, or do anything to loose focus on your game, it will loose its media. I think windowed mode avoids this issue, so use that, or fullscreen windowed. The other alternative is to setup all your media again when this happens - like use a function to load and setup your 3D media and textures, and call it when object 1 disappears - check for it on each sync and re-load the media if needed.
This can be a real pain if you have popups - like RealPlayer wants to do an update, then it'll take focus for it's little window, and crash your program - same goes for anti-virus software. These days I like to use a media setup function that can be re-called, especially for platforms like the Netbook and AppUp.
Health, Ammo, and bacon and eggs!
