The very first result of my online search showed that this is a pretty common issue with that lens. :/
https://photo.stackexchange.com/questions/85579/weird-canon-17-55-f2-8-is-lens-error
https://www.dpreview.com/forums/thread/3934584
Must have been a bad design that breaks too easily. You might try turning off IS and see if that helps. Some people said it only seems to happen with IS on. https://www.flickr.com/groups/81487468@N00/discuss/72157603629201326/