That don't work for everyone Chile, it never worked for me, this must be the most posted about problem on the forum, there are lots of potential fixes but what works for one might not work for another, as stated it is a sound problem, sometimes updating your sound drivers may work, another cause may be because you have already just updated your sound drivers and it has just started straight after that, if so roll your drivers back, sometimes i have had to uninstall game then update sound drivers then reinstall game to my new drivers. If you google iw3mp.exe you will see it is a very common problem, there are many potential fixes but as i said what works for me might not work for others.