When players (using Windows 7) try to activate "Day of Defeat: Source" (DODS) from their Steam games list, it won't run.

Steam says that the game is running, but nothing happens, no matter how long you leave it.
Nor will Steam let you shut down the game.



How to shut down the phantom "Day of Defeat: Source":
-- Hit "Ctrl-Alt-Delete", to bring up the Window's Task Manager.
-- Although it won't show "Day of Defeat: Source" in the Programs tab, it will show "hl2.exe" in the Processes tab.
-- You can shut down DODS by clicking on "hl2.exe" and then clicking on the "End process" button.

Bring up your "regedit" programme
-- click on the Windows start button (at the lower left of your screen)
-- type "regedit" (without the quotation marks) in the search bar (i.e. where it says "Search programs and files")
-- double-click on the "regedit" programme's icon in the search results

Go to the following location:
"Computer / HKEY_CLASSES_ROOT / Local Settings / Software / Microsoft / Windows / GameUX / ServiceLocation"
-- right-click on the file called "Games"
-- from the right-click menu, choose the option "Modify"
-- delete the text from the line named "Value data" (just leave it blank, nothing needs to be in there), and hit the "OK" button.

That should fix your problem.



The text in the "Value data" line on my computer was:
"games.metaservices.microsoft.com/games/SGamesWebService.asmx"
(with "https://" at the start of that line - for some reason the guide won't show the full address if the "https://" is left at the start of it)
-- apparently this line causes your computer to try to connect to the internet, and ends up causing a loop when you try to launch the game.

Thanks to "cisticola", who posted the solution in the Steam discussions re. this problem.
Great work!