This is the fix for Half-Life 1 Single Player not working(Freezing while Starting Local Game Server)
If you are opt into the "Steam Beta Update" It will sometimes break a lot of your games because it is updating with unofficially released updates. To disable it,
-Open up Steam
-Click on the Steam tab in the top left corner of the page
-Under the Account tab there should be an option for beta participation
-Set Beta Participation to "NONE - opt out of all beta programs"
-When it asks you to Restart steam, click Restart
The Steam client should then restart and update itself to the correct version and you should be able to play without any problems