Hey guys! This fixed the issue for me , hope it works for you to =)

http://forums.logitech.com/t5/PC-Gaming/The-Witcher-2-G35-FIX-without-uninstalling-Logitech-drivers/m-p/624220

i have the same problem, but what is G35? i just lost almost all sounds... patch 1.1 not just doesn't fix the problem but i think it caused it... so wait till next week for the next patch?

For those of you with XP, try reducing Hardware Acceleration.

I dunno if it'll help you guys with this game or any others but I got this fix to work for one of mine!!!

INSTRUCTIONS:
Go to the default.ini file located in the data folder of your game in the install directory. Open with notepad.

Scroll to the bottom and locate # Integer parameter
setf ~cl_force_soundcard -1 change the 1 to a 0 so it should now look like this

# Integer parameter
setf ~cl_force_soundcard -0


Let me know if this helps!!!