Cache Needs Repair error
From Valve Developer Community
This error occurs when certain game cache files have encountered an internal problem (usually after a crash while running a game).
To repair the cache file:
- Shutdown Steam by choosing Exit from the Steam task bar icon menu.
- Restart Steam.
- Run Half-Life: 2 from the Steam Play Games window.
- If the problem is not resolved, repeat these steps running Counter-Strike: Source and Half-Life 2: Deathmatch.
Running these applications causes them to validate and repair any cache problems they may have.
