For years, I've had problems with my 10-22 lens. When I try to take a picture it usually gives me either an Error 99 (Rebel XTi) or an Error 1 (50D). I don't know why, and many professionals have looked at the lens and been baffled. Sometimes, though, it'll work for days at a time. I can't tell you how many times I've heard "oh, just take an eraser to the contacts. It'll be good as new." Since this happens on every body I've put the lens on, I'm positive that it's the lens. But I accidentally found a way to make it consistently work: don't lock it in all the way when I put the lens on the body. When I leave about one centimeter left before it clicks in, the lens works every time. Obviously I'm pretty happy that I can get it to work, but I'd like to know if anyone has any ideas about why this particular method causes the lens to always work. Or if anyone can come up with a good way to let me lock in the lens and still be able to use it. Thanks.