Found solution here!
Posted for anyone else having problems and comes to this page via Google:
I'm running Windows Vista or Windows 7, and some or all of my GoldSrc games (Half-Life, Half-Life: Blue Shift, Opposing Force, Counter-Strike, Day of Defeat, Team Fortress Classic) will get to the loading screen just before the menu appears, then crash to desktop. How can I fix this?
Data Execution Prevention
This may be caused by Data Execution Prevention (DEP) which is a security feature enabled on recent operating systems. Older games, such as GoldSrc games, were not created with DEP in mind and may trigger DEP's security features inadvertently. Please try the following:
1.Go to Start > Control Panel > System > Advanced > Performance > Data Execution Prevention.
2.Select "Turn on DEP for all programs and services except those I select:"
3.Select "Add", navigate to C:\Program Files\Steam (or your default Steam directory), and add Steam.exe to the exception list.
4.Additionally, you will need to add the executable (hl.exe, for example) for any game you are seeing issues with. These files will either be in \Steam\steamapps\common\\ or in \Steam\steamapps\\\