This has been discussed several times already, and it's not a problem with any of our programs but, instead, a problem of your Windows installation, related to the MS Visual C++ runtime libraries, which the Couatl.exe program requires, that are missing/corrupted or the wrong version.
Try to follow all the solutions proposed in this thread:
http://www.fsdreamteam.com/forum/index.php?topic=6754.msg58130#msg58130In this case, what fixed the problem for that user, was creating a new user account and run FSX and GSX on it, which was clearly an indication that something was wrong in his Windows install, and creating a new user fixed it in some way.
Another possible cause of this, is a bug of your audio drivers. Sometimes it's best to use the default audio drivers that comes with Windows, sometimes it's best to use the one supplied by the mainboard or audio card manufacturer, it depends.