Does it matter which program you open first, or does the audio problem happen either way?
By "hear VC," are you referring to TTS responses in VC, or something else?
Are both applications using a single, shared audio output?
If they're both trying to access the same audio output device, check your audio output Advanced properties. Maybe you have exclusive mode properties enabled or something like that.
If you have more than one audio output option, try to set VC to use a different audio output than whatever Guile is using. The default TTS audio output in VC can be selected in the TTS plugin settings.