Answer to: Power on problem on 50DHi...I had the same problem. It was all the CF card to blame. There is a reset procedure by which you open the battery slot, remove battery, open card slot, push out the card. Pause...Push back card and close battery, pause 2 sec, push in battery and close lid. All back to normal. It was all due to a corrupt card...I repeated this over and over with my 8GB card and it never went bad again...The moment I put back the 4GB all symptoms reappeared..