Last night while I was shooting hockey I got an ERROR 99 message on my 40D. It said to reinstall the batteries. After I did that it was fine. I use a 70-200 2.8 lens which I've had for about 5 years and have never had problems with it. I've had the camera since August. This is the first time this has happened. Does anyone know what causes this? It was the first time I shot with a Sandisk ULTRA II 4GB card, I usually use my Lexar Prof. 300x 4GB card, don't know if this could be an issue. Thanks.