I've been playing for 4-5 hours, quicksaving along the way, and doing manual saves as well. After saving, and quitting for and hour or two, I start the program and I now only have the quicksave and autosave from the character creation phase (5 min. into the game), and a manual save 2 hours into the game. What the !?!?!?!?!

How can I play this game!? If I do, the saves will be lost! Does this mean that in order to play, I have to back-up my save game files every single time?

Same thing is happening to me. Steam says I have 8 hours in but my saves games are from Tuesday with only 3 hours. FAIL.

This is known and being worked on. There are some pinned threads that address the issue in the Software and Hardware sections for FO:NV. Please read them then share your problems in the appropriate open threads over there as that is where this discussion belongs. I'm so sorry you are having problems.