Even though I'm in Canada, there are ways to get what you want... hehe
My setup is pretty much the same.
I have the voice widget for left messages.
I never had this google voice issue... until yesterday!?
Like... wtf man... what did you do to my phone?
No seriously, that is weird.
I close gvoice and it instantly reappears/reopens so I have to close it again.
I tried with and without any minfree tweaks but still the same.
It may be a CM7 issue. I dunno.