Hace poco un compañero tambien tuvo ese problema. Te paso el enlace con el que lo solucionó con vista: http://www.evilavatar.com/forums/showthread.php?s=fb7f17d70fcfdafc352e32a9192b9abb&p=1712402#post1712402

El Tocho:
*** PC Patch 1.2 Audio + Mod Problems – explained ***

It is clear that some of you are experiencing problems with the 1.2 patch. First, we apologize for any additional inconvenience this has caused. After some time reviewing the feedback, it is clear there are two main issues.

Audio Problems:
A select number of Vista users are reporting that all sound in the game is no longer audible after patching to 1.2. We will be including a permanent solution in our 1.3 patch. In the mean time, a work-around fix has been discovered, and instructions are located at this post: http://www.callofduty.com/board/view…?f=29&t=101457

Mod Problems:
While HTTP Redirect is fixed (so you can download custom maps + mods from the web, in-game) it appears some mods may no longer be functional after patching to 1.2. At first glance this would appear to be a new bug, but after some digging we determined this problem is actually with the mods themselves, and here is why:

In the process of addressing issues for Patch 1.2, we had to add new DVARs to the game for development purposes. Modders, you know what we mean when we say DVARs. There is a hard limit to the number of server DVAR’s that can be used, for network latency (lag) reasons. So when you run a mod, the game DVAR’s load first, then the mod DVAR’s come second. If the additional mod DVARs exceed that hard limit, it will not load. That was the problem in a nutshell with today’s 1.2 compatibility. Since we added additional DVAR’s, the mods spilled over that max limit.

The solution for modders – use server DVAR’s sparingly. When possible, set client DVAR’s. There is no guarantee we won’t add more DVAR’s in the future as these are a core component to our development process, so you want to prune down your DVAR’s as much as possible to avoid future compatibility hassles. We support and maintain our mod tools – however, we are not able to maintain compatibility with mods, nor is this our responsibility. By definition, a mod is user-generated content and must conform to the technical limits of the game.

We have already begun work on a 1.3 patch which is slated to release this month as well. Along with /record, we will include a more permanent fix for the audio issues.

More update will follow.

*** FIX: Vista Audio Problems with Patch 1.2 ***

Just a quick update – this fix should solve the problem some Vista users are experiencing with lack of audio in CoD:WaW after patching to 1.2:

Method A:

* Right-click on the Volume icon in the taskbar (next to the clock, looks like a speaker)
* Select ‘Playback Devices’
* Right-click on your preferred playback device (i.e. Speakers, Headphones, etc.)
* Select ‘Properties’, then click the ‘Advanced’ tab
* Set the Default Format here to ‘16bit,44100Hz(CD Quality)’

Note: You may reach the same menu in Method A through Control Panel > Sound.

Method B – Advanced users only (perform at your own risk!):

* Right-click on My Computer and select ‘Manage’
* Select Device Manager and expand ‘Sound, video, and games controllers’
* Uninstall listed Audio Drivers then reboot the computer
* Vista will now auto-reinstall the on-board sound
* Default Format is now set to ‘16bit,44100Hz(CD Quality)’ automatically

Please note that setting your audio quality to 16-bit will not impact your Call of Duty: World at War gaming experience. The game will sound just as good as it did before, as our sounds are mixed at 16-bit.

Espero que te sirva