This explains a lot... I had this issue with the 1Ds2 bigtime. At least now they are offering a free cleaning -- with my 1Ds2 it took me a couple of hours and $50 worth of swabs and Eclipse to get it clean. Good news is it sounds like Canon is finally taking a proactive approach to quality control issues and the related customer service:
http://www.usa.canon.com/consumer/c...oryid=215&modelid=15710&keycode=2112&id=57853
http://www.usa.canon.com/consumer/c...oryid=215&modelid=15710&keycode=2112&id=57853