Canon 7D, Sandisk Extreme Pro 16gig CF, three Canon OEM LP-6E batteries.


Whenever I remove the CF card to transfer the pictures into my computer, then reinsert the card back into my camera, the camera won't turn on. I have to remove the battery, the put that back in at which point the camera fires up as normal. Also, if I don't put the CF card back, the battery drains (the camera is of course, off). Has anyone encountered this before? Aside from that, the camera works just find.