Sound skips or stutters

http://support.steampowered.com/cgi-bin/steampowered.cfg/php/enduser/std_adp.php?p_faqid=280

Sounds skipping or stuttering periodically may be caused by outdated video drivers, running graphics at detail levels your hardware cannot support, or fragmented cache files.

Please run the Steam Performance Test and correct any issues which it identifies.

Run the Steam Performance Test: steam://support/?Issues=Performance*

Confirm that your video drivers are updated - see the FAQ linked below for full instructions:

Updating Video Drivers http://support.steampowered.com/cgi-bin/steampowered.cfg/php/enduser/std_adp.php?p_faqid=422

Optimize Video Settings From the startup splash screen for the game, select "Options" or "Settings" then "Video" and switch to the "Advanced Settings" tab.

Turn down (or off) anti-aliasing completely - many cards should be defaulting to no AA Lower your video resolution one step Drop texture level down one setting - this will slightly degrade the visual quality of the textures in the game Set the Shadow and Shader Detail to "low" For full instructions on optimizing video settings, please see the FAQ linked below:

Reset Video Settings and Force a Video Mode http://support.steampowered.com/cgi-bin/steampowered.cfg/php/enduser/std_adp.php?p_faqid=242

If you are encountering very long loading times and sound skipping or stuttering, the issue may be related to cache file fragmentation (if your cache files are split up over different locations on your hard drive, loading sounds and maps will take significantly longer than it would if the data were stored in the same place).

Please follow the link below for more information on defragmenting your game's cache files (GCF's):

Defragmenting Game Cache Files http://support.steampowered.com/cgi-bin/steampowered.cfg/php/enduser/std_adp.php?p_faqid=468