I have this problem too... Doesn't seem to matter which app one are using, it also happens with my golf app... And the only way to fix it, is to reboot the phone.. This is really annoying...
It seems to be related to bluetooth use... If I use BT to play music/listen to audiobook at the same time as I use the navigation app, then I have this problem.. If I turn off the BT, then the problem does not seem to appear... I am saying seem to, because it seems to be random when this occurs so not 100% sure that turning off BT fixes the problem but so far I have not had this problem when BT is off..
I also thought this was fixed in the latest update but yesterday it happend again....
"I understand that if you play a Windows CD backwards you hear strange Satanic messages"
To which someone replied:
"It's even worse than that; play it forwards and it installs Windows"