I know, yet another Error 99 post about a 40d, however after reading through the other threads, mine seems to be a little different.
Ive had my 40d for about 2 months now after buying it on ebay (replacing my 350d which died of, you guessed it, error 99)
I had it appear today whilst shooting a tennis tournament (of all times for it to fail). Ive tried everything suggested all over the interwebs, but to no avail.
However, when on Live View silent shoot, it works!!
Live view on normal shooting it doesnt, however when on silent mode 1 or 2, it does!!
What does this mean is wrong? the mirror? shutter mechanism?
Ill get it repaired, but i just thought it would be interesting to know what you guys think,
Thanks , sam 

