Yes, this one I can help with. I had the same exact issue during the beta test, as part of my week-long journey to get VOIP to work. I recommended to Tripwire that they disable the ability for a user to remove the checkbox from the "System Driver" setting, for exactly the reason that you're asking about it.

Here's what you need to do to get back up and running:

Go into the directory where the Red Orchestra system files are stored, which should be found on your hard drive at a location similar to the following:

C:\....\Valve\Steam\SteamApps\<steam username>\red orchestra\System


In that directory, find and open the file called RedOrchestra.ini. Within that file, do a search for a line that looks like this:

[ALAudio.ALAudioSubsystem]


Below that line, make sure your settings look like this:

UseEAX=False
Use3DSound=False
UseDefaultDriver=True
CompatibilityMode=False
MaxEAXVersion=255
UsePrecache=True
ReverseStereo=False
Channels=32
MusicVolume=0.000000
AmbientVolume=0.500000
SoundVolume=0.900000
VoiceVolume=10.000000
VolumeScaleRec=0.100000
DopplerFactor=1.000000
Rolloff=0.500000
TimeBetweenHWUpdates=15.000000
DisablePitch=False
LowQualitySound=False
UseVoIP=True
UseVAD=False
UseSpatializedVoice=False
SpatializedVoiceRadius=100000.000000
EnhancedDenoiser=False
LocalZOffset=0.000000
DampenWithVoIP=True


The first three settings are probably the most important, but setting them all is probably a good idea. Save RedOrchestra.ini, and then try to start up the game.