I am having the same issue. The image jumps from the very first shot, but sometimes it works just fine. I took the lens to Canon but they want to charge me $100 just for the diagnostics, and repairs will cost upwards of $500 so I didn't get it fixed. I am hoping the next firmware upgrade may resolve the issue. As I don't have any important shoot coming up I am reluctant to fork out $500+ to fix this issue. It only jumps when IS is turned on.
