Originally Posted by
rabidfox
Try manual adjusting the userpreference file under mydocuments folder (be sure to back it up first). Sometimes setting "ScreenMode=FullScreenWindowed" helps.
Also are running on laptop with trackpad or a desktop using a trackball? Another user mentioned DDO can be weird and crash out if doesn't detect a real mouse, so under those conditions, plugging in a usb mouse can help.
u50 changed the default client to use the 64-bit version, so could also trying under the launcher settings to swap it back to the 32-bit client and see it that helps (drop down arrow in the launcher>options)
There's also various other fixes/ideas that are out there in other recent threads that you could probably search for.