I wonder if any of these issues may be related to any customization that may have been done to the individual camera and the interaction with the software update. I was having crashes fairly regularly that would always be fixed with removing the battery and rebooting. This continued after Canon replaced the motherboard on my camera. I downloaded the 1.5.0 update and my camera became almost nonfunctional--crashing after every 10-20 photographs, terrible focusing abilities--this was while I was at Bosque. The IS would make horrible noises. I was making plans to send it back to Canon insisting that it be replaced because it was so bad. I have to disclose that I had my camera extensively customized with 3 !! back button focus buttons--one for single point, one for eye, and one for zone and had changed the functions of other buttons so that they could easily accommodate my reach. I had also had other Canon pros including Explorers of Light add their modifications to my camera along the way. When I returned from Bosque, I decided as one last desperate try, I would reset the camera to factory settings (except for the My Menu favorites at the end) and start over. I programed a single BBF and changed a dial to modify ISO and now I cannot get my camera to crash on tests I have done around my home with the RF 35 or RF 100-500. Focusing seems to be excellent for the birds around my house. There is no noise that I can hear from the IS unit. There was a comment I read on the forum here that said it was possible to create some conflicts between customization and the software. I now believe that this has been my problem all along and that I owe Canon a big apology.
Catherine