Acer N300 sound and Tom Tom 6

I have an Acer n300 on which I want to run Tom Tom 6. At the end of the installation it asks me to restart (soft reset?) the system. If I do this then there is then no sound output at all from anything and it comes up with a
message "Error 0x37 opening WAV driver."
If I opt not to restart the system then the sound works OK which would seem like the obvious way to do things.
The problem is if I need to change the battery for a freshly charged one, the system restarts and the sound no longer works. I suspect that there is a
registry mod connected with the Tom Tom installation that could correct this? Any help would be much appreciated.
Thanks