2007 TL/NAV.

I have looked through many of the forums and posts, and haven't found an answer. My NaviTalk (voice command) button stopped working. It will work every 100 times I try, but otherwise does not work. My HFL Bluetooth works perfectly. Any ideas?

Note: I did load the 2012 maps DVD (with no problems) last year, and don't know if this could have caused this. I had the 2010 DVD prior, and did not seem to have any issues. I also had no other NAV issues now. I am stumped. Please help.