very strange problem opening the file

Hi there,
It is a nightmare! I have this habit of quitting Scrivener without closing the project first, and then I go to my other device and open the same file that has been synced through Dropbox. Instead of getting a warning to make a copy, the .scrv file could be corrupted as my experience told me. By corrupted, I mean the Scrivener refuses to open my file and shut itself off. The computer screen goes dark for a friction of a second and then the windows pops up saying it has a problem and ask me to ignore it or report it. Knowing that I am forgetful, I always physically kept a backup after each use in a none-syncing folder. However, the worst thing happened tonight. After realizing I doubled open the file again, I went back to my 1st device. I tried to open the same file in Dropbox but failed because the corrupted file has been synced back from my 2nd device to the 1st. I thought I was lucky to have a backup but the backup won’t open neither! Scrivener fails to open it! Same dark screen! I don’t think the backup file been corrupted. No way! My guess is that there is a something wrong with Scrivener cache file, but I am not sure what to do with it. Scrivener works well on other projects though. This is a book project I have been working on for 3 years. I must rescue it. Please help.