If you are receiving this error:
Doing so may resolve your concern.
When installed on Windows Vista or 7, the game creates its icon in the "Games" panel. You can access the Games panel via the start menu. Inside the games panel you should see an icon for DDO.
If for any reason that icon does not display or does not launch the game, you can create one manually by following the steps below:
In that folder look for "TurbineInvoker.exe" (it might display without the .exe but it will be the one listed as an "application" and will have the red DDO "shield" icon).
Right-click on that file and choose "Send to" > "Desktop (Create Shortcut)" and that will create a desktop shortcut to launch the game from.