Originally Posted by tomrock
Wasn't this a pretty common problem when the 20D was new? Have you checked the firmware? I would guess that if you sent it to Canon they did but you never know.
I still have the original firmware as when I bought the camera about one week after it hit the market. I've taken 20,000 or so photos with it and only 2 or 3 times every had a lockup. I don't recall that being one of the problems. When I would look at the firmware fixes, they always seem to be for something that I had no problem with. I know that any electronic device will occasionally lock up. But if it takes only a few seconds to clear it and it only happens 2 or 3 times in 2 years, then it is of no real importance, in my view.
Now in user numee's case, it does sound like a problem and if it happens with all the lens he has and with each memory card, then its likely the camera. But a bad memory card can cause lockups and a lens problem (usually with the connection point to the body) can also be the culprit.