I have searched the forum and cannot find an answer to my problem. For the last two (2) days, I have gotten this message on my camera when I tried to shoot: Error 20 Shooting is not possible. Turn the power switch to and again or re-install the battery. I have replace the battery; replaced the CF card; changed the lens (I had my 200mm, and went to my 300mm and 400mm); and tried to clean the contacts. The camera body is approximately two (2) years old (out of warranty). Does anyone KNOW what else can be done to fix it, or should I contact Canon Support? Thanks in advance for your help.