Half Life 2 does not want to start please help

[ThePunisher]

Hi guys I just bought Half Life 2 and went through the whole activation and activation.
When I click on the Half Life 2 to start playing this error comes up.
Failed to load launcher DLL:
I have reinstalled game and tried everything any help would be great as I am so desperate to play game.
Thanks

 

[Deemo]

try validating the HL2 files:

steam://validate/220

just stick that in your web browser and itll start verification