Voice Control randomly turns on

I have a problem that is driving me crazy. I purchased a 32gb iPhone 3GS about 3 months ago and I have had an issue with the voice control since the day I brought it home. I have an auxiliary audio jack in my car so I always connect my iPhone to my car stereo to play music. For some reason whenever my iPhone is connected in this way the voice control constantly comes on.

I understand that holding down the home button on the face of the phone is what is "supposed" to bring up the voice control option but that is not the case in this instance. Rather I will be listening to music, or simply pick the phone up while connected so I can change the song (but before I have actually touched any part of the phone) and the voice control will come on - stopping the song and forcing me to hit "cancel" in order to get back to the music. This is incredibly frustrating because it's happening while I drive and what makes it worse is the fact that since the phone is on voice control, and connected to my stereo, whenever I move it the sharp crackling from sound going through the microphone is broadcast through my car's speakers.

I have read through a few threads and there doesn't seem to be any way to deactivate voice control - but I could be wrong. Does anyone have any idea how to permanently shut off voice control? Has anyone else had this same problem? I can't figure out why this would be happening or what I can do to prevent it. Thanks for any help you can give me.