https://help.standingstonegames.com/...s/115002036707
Run it as Admin once, sometimes that allows it through? Run it in windowed mode, maybe there's an error message popping you can't see?
Are there any other programs running? Anything at all that might be listening on the ports DDO uses? Try turning everying else off, closing everything else.
You're sure there is no firewall stopping it? Windows has its own firewall, your router may have a firewall, Anti-Virus programs might have their own firewall.
What anti-virus are you running? Try turning it off, or turning off real-time protection ( turn it back on right away) and see if it works?
Directx9.0 installed? Visual studio redistributables?
https://help.standingstonegames.com/...s/requests/new