Boot time driver conflict

I have a Microdia web cam. Some times it won't work if and only if there is a "HV7131R image sensor detected" statement in the boot up.
In this case when I try to get a .png snapshot all I get is a frame full of what appears to be white noise only it is mostly green.
Here is the command I am using:
TV="-tv driver=v4l2:device=/dev/video${vd}:width=320:height=240:norm=NTSC:chanlist=us-cable:input=0:noaudio:outfmt=i420"
OUT="-fps 30 -cache 128"
PIC="-hue 0 -brightness 0 -contrast 0 -saturation 0 -aspect 4:3"
mplayer tv:// $TV $OUT $PIC -vf screenshot -vo xv,x11,
This does not work when ${vd} is 0 or 1 and it is using HV7131R.
If it is not using HV7131R it works properly.
I think I am getting either gspca or HV7131R usage defined at boot time. Is there a way to force either one so I can test?
Hope it is OK here as the problem occurs in my script.