OK, this is new one. If I turn the unit on then attach the USB lead which is plugged into PC the unit turns off! Any ideas?
So...
GPS on, USB in unit, plug other end into PC (OFF), then GPS turns off...
GPS on, USB in unit, plug other end into PC (ON), then GPS turns off...
GPS off, USB out of unit, GPS turns on...
Upate. managed to get the unit not to power off by connected with PC in sleep. But the unit is not recognised by mapsource and the external power indicator is not off. Then unit randomly turned off.
Repeated this last method, when PC booted up again, unit turned off.
I suppose I could ignore the USB connection...and use the microSD for transfers.