I could change the program so it checks the volume settings when it starts, and then restores those settings when the program closes.
However, before I change anything, I want to understand the problem a little better, since I don't think I've heard of this happening before.
What OS are you on?
Can you open up the settings file DriveLine_Settings.XML, search for WAVEOUTVOLUMEMUTE, and let me know if it's set to True or False. It sounds like maybe this somehow got set to TRUE. Like, if you muted the wave-out volume through the Pandora screen this could possibly happen.
edit: one more question -- you are referring to the Speakers volume, right?