Right here goes,

If I quit Nero and return it is ok. So it is when I shut down my pc and then start it again.
I haven't got any other firewire devices I can run.
I have a VCR hooked up to it.
If I unplug it and then put it back in the same port (while the pc is running) it is ok.

So it seems to be every time I shut down pc then start it up?