EOS1D downloading

[PaulB]

Anyone come across this before?
Downloading the images from a 1D to PC via Firewire.
The first CF card works fine. Remove card 1 and insert card 2 into camera. Result is a lost connection.
Only remedy is to reboot everything.....Camera and PC.
Canon say swopping cards should be fine, but it isn't with this setup.
Camera firmware updated, as is Canon software. PC recently been upgraded - used to do this with old setup (PCI firewire card) New M/B has firewire on board.
Answers anyone?

Thanks in advance.