The most common causes I know of.

1. The Windows was installed by a shop that didn't know to install motherboard and more drivers.
2. The firewire port is blown. Test the camera on another PC.
3. The camcorder is not in the right mode. See manual (I won't guess this one.)
4. The USB means ZIP here. Nice detail but means so little.

JVC Tech here was good but then at 120 per hour...