Two more problems that are usually easy to fix: search for QNAN and #INF and replace with a 0. Sometimes Maya gets an infinite number (the second one) - and the first is not a number. You'll see a camera transform in the .ma file that's like: 23.QNAN so if you replace it with a zero it will work.
I posted this on GA.org, but I'll share with ya'll. The best protection from loosing your work is iteration saving. OFTEN. Although you can't protect yourself from spontaneous disk failure. That being said here is a tutorial on recovering Maya Ascii AND Maya Binary files. It is really easy to do, but will be tedious. This…