I've had my 5D MkII since November 08, now I've been experiencing this transfer issue for a while now although i was hoping it was going to be fixed with the firmware update although the problem still persists.
What happens is when my 8GB Sandisk Extreme 4 UDMA card is in my 5DMKII and i connect it up with my Apple MacBook Pro17" via USB2, it will transfer 1/2 of the images and then just "hang" and eventually crash leaving me to force quit the canon software which came provided and start again. I can just select Transfer New Images which downloads the rest of the images but obviously this is a pain either way.
I don't have a card reader that support UDMA so i have been using direct tranfer with the provided software from Canon (which has been updated to the latest versions).
Also this ONLY happens when I have taken more then 200+ images on the card. Anything under that amount will transfer with no problems.
Any ideas?