Recently Samsung Magician came out with the 4.5 update. After this update was installed on my machine, I was unable to play DDO through Steam, due to the mouse turning into the regular system mouse pointer, and being unable to click on anything for the screen. It appeared that there was an invisible window on top of the DDO screen, and when I clicked on it, DDO would minimize.
The solution was to disable Samsung Magician from running. The Samsung Magician app does NOT need to be running for the Samsung SSD's to work correctly, it only needs to run to check for updates to itself or the firmware on the Samsung SSD. If you right click on the Samsung Magician application icon in the notification area, it will allow you to not run it on boot, as well as exit the application.
This was on Windows 7 with the latest patches.
Hope this helps someone!