Have you been having problems with launching Half Life 2 or Half Life: Source recently? I can help. If you’ve been getting the error message ‘Failed to load the launcher DLL: The specified procedure cannot be found’, you’re in the right place. If you are getting these messages when trying to launch Portal 2, Dota 2 or Alien Swarm, make sure your computer or laptop is compatible with Streaming SIMD Extensions 2 (SSE2). If it is just Half Life 2, or Half Life: Source, here is a quick, fast solution for you. Please note that if you cannot launch Half Life: Source and do not have Half Life 2, this will not work for you and you do need Half Life 2 to fix this bug currently.
Go to your Steam games library, select Half Life 2 and right click it. Click properties, right at the bottom of the tab that has appeared. Next, select ‘Local Files’ and click on the button that says ‘Verify integrity of game cache’. Wait for it to finish verifying and then try launching Half Life 2. The game should fully work and you should be able to play without interruption.
If you’re looking to play Half Life: Source, make sure you do the steps above and verify the Half Life 2 files. Then, do the exact same thing for Half Life: Source and this should fix the problem for good. I hope this bug fix helped.