Já vi gente reclamando deste erro no DPReview e Flickr o problema é relacionado ao mecanismo de disparo.
DPREview =>
http://forums.dpreview.com/forums/readflat.asp?forum=1032&message=30404535&changemode=1E tem no Flick também =>
http://www.flickr.com/groups/eos50d/discuss/72157621253591642/Tabelinha para auxílio, nao sei se vale ainda, mas taí:
10 - Malfunction related to files has been detected.
20 - Malfunction related to the mechanical mechanism has been detected.
30 - Malfunction related to the shutter has been detected.
40 - Malfunction related to the power source has been detected.
50 - Malfunction related to the electric control has been detected.
60 - not used
70 - Malfunction related to images has been detected.
80 - Malfunction related to the electric control of images has been detected.
90 - not used