My first Canon DSLR was a 300D. I used to get "error 99" if I tried to use my old Sigma lenses which had worked well with my film Canons. I believe it is "non specific errors, i.e.ones that do not fall into the usual categories, or Canon's way of saying "don't ask us, we don't know either."
I think error 99 means search down the purestorm forums and find another 40d for sale that doesnt hve any errors Just kidding, hope you get it sorted. whenever i have had error 99 it generally means Canon is telling you an error but has no idea what error
Someone is selling a 40D on here at a good price....in your situation I would think about buying it. If you fix your camera yourself you have another decent back-up.....if not, you have another 40D at a price that is possibly not much more than the repair bill for your current body......and this one has a Canon grip included!
Hi Am not sure if it is the same model, But I came across this several months ago it could be a design fault with the camera. You cant shoot quick it is because it stacks the images up and needs time to read them.so you have to wait until the camera can do this, It needs to go back to cannon, before you do this contact cannon. If you are still under guarantee I was told cannon will sort out. I got this information from a shop in London who deals mainly with cannon cameras. Hope it helps Cliff