Canon 40D freezing up till I remove the battery...

[lale]

Every so often, my Canon 40D has an issue where when I try to take a picture, it freezes up.

I click the shutter, shutter closes, then the camera turns itself off with the shutter closed. I remove the battery, put the battery back in and the shutter opens again, but no image is on the card.

Usually this resolves itself after a few minutes. Any ideas on what the problem is?

lale

[CaptainNH]

I used to get this with my 10D very occasionally. This is almost certainly a problem writing to the card.

My suggestion would be:
1. Jump on the Canon website and make sure you have the latest firmware.
2. Reformat your CF card(s) in camera.

If this doesn't fix your problem, it's time for a trip to the camera doctor.