Game crashes are caused by a few different things, your system hardware, software or drivers. The HL2.exe has stopped working is typically caused by an application conflict. Here are a few troubleshooting tips we can try.
Note: At the time of this post, several hotfixes available for Vista users, specifically Vista users with Nvidia cards. It’s out of the ordinary that Nvidia would us a problem. Normally it’s AMD to blame for BSOD or game crashes.
Anti-Virus Software
When it comes to correcting the HL2.exe has stopped working error, anti-virus and anti-spyware software has been the cause. Simply disabling these applications would prevent the error from appearing.
Anti-virus applications such as Norton, AVG, Avast, and Nod32 have been confirmed by Valve to cause game crashes with source engine games. If disabling anti-virus or security applications provide no help, consider uninstalling all anti-virus applications until an update is released.
Background Applications
Graphic intense games like Half-Life 2: Episode Two and Team Fortress 2, require a large amount of system resources. Background applications running during gameplay can often result in the game engine competing with other applications for system resources. This can result in the game crashing due to lack of system resources free for the game to utilize.
HL2.exe Has Stopped Working
It is important to make sure that your system has enough paged pool memory available. Please follow this guide for more information.