I use my EF100-400 on a Canon 10D. While in IS and auto focus mode, I was shooting a soccer match when the lens abruptly failed to focus, and I got an error message on the camera. I turned off the camera, removed the lens and remounted it. The lens would focus and the stabilizer would work, but after focusing and stabilizing the subject, the image in the viewfinder would abruptly shift to the left then pulsate.
My lens has worked perfectly since purchased on 2002. I can't find any information on troubleshooting or the problem I'm having. Can anyone out there help me or point me to a resource?