I believe it could also be a driver issue with soundblaster as I've recently encountered my rdp (mstsc.exe) crashing whenever sound attempts to pass through the connection, which is a software based issue. I found by rolling back my bios to A08 and then up to A09 I've encountered the issue less frequently and a shutdown/startup can resolve it. I can bring back devices by flashing the bios, but that's a pain, just seems to be a temporary work around. I've been having this issue on my m18x r2 for about 2 months now, along with random webcam loss. So all I can say to Creative is HURRY YOUR ASS, and to Alienware Light A Fire Under Creative's Ass!
I think the only thing that we can do right now is wait until Creative comes out with a driver update that won't pooch the sound! Obviously there are some bugs to fix for them right now, and yes it is a big inconvenience to all of us, especially since we have paid good money for great machines, but this sound card problem is really getting on my nerves as I sure it is with all of you too.
Once I have done that my sound is back and everything is working normally until the sound conks out again and I have to restart my machine once if not several times to get it working again. I have had to revert the PC back to a state before the Creative Sound Blaster Recon3Di update.
But what ever you do, do not update the driver right now! each time that I have upgraded the driver the sound is permanently gone, and none on the jacks will work either. From what I have found it is hit and miss with the original audio driver. I have been having the same problem since I received my new M14x R2 in December of 2012.