Something got corrupted last night on my mid-2012 unibody MBP with recent upgrade to El Capitan. After logging in to either my regular account or the admin account, I get a grey screen and a large Apple and that is as far as I get. I tried booting up with Command + V selected for a verbose look at what is happening. I see that it has several lines saying there are errors, but I don't have time to write it all down. Once my data is backed up, is there a way to fix this issue without wiping all of my data and settings? It takes me several days to rebuild a machine with all of the software I run, and that makes me want to cry. There must be some way to at least temporarily fix things so I can get booted back into my MBP.