We are investigating an issue with machines running the 64-bit Beta DDO client on an NVidia graphics card. In the meantime we would like to pass along a workaround that should get your issue resolved for now. This corrects an issue where the launcher disappears when trying to enter a game world:
1. Open Windows Search, Type: "Nvidia Control Panel", and run the result.
2. Click "Manage 3D settings"
3. Click the "Program Settings" tab
4. Click the "Add" button
5. In the add list, find dndclient64.exe (must have already tried to run 64bit DDO for it to appear)
6. Select dndclient64.exe and click "Add Selected Program"
7. Click the dropdown box under the new selection, and choose "High-performance NVIDIA processor"
Please note that players can also switch back to the 32-bit client through the Options menu in the game launcher.