So I installed El Capitan and it mostly works fine. However, I can't access a USB receiver that I use in teaching my classes (TurningPoint 5.0). It appears that USB recognition has been a problem for some people on all the releases of El Capitan. FYI, I'm currently on the GM Candidate. I think I need to revert back to Yosemite so that I can use this critical functionality. Although I made a backup using Yosemite in Time Machine, I deleted it when I backed up to install the GM. Is there any way that I can still back up to Yosemite, or do I need a Yosemite backup? Thanks for any help you can offer!