This is more of a bug report instead of support question, couldn't find a bug report topic, there should be one.
This has happened at least 10 times to me in the short 2 months i been playing minecraft, and they are TERRIBLY annoying when they happen. Ill save a game, quit, get back on later then i find out that either im in the same spot i was when i saved, but everything I did since several saves back is gone and back to the state it was several saves back, or it will just put me in several saves back entirely position and all losing ALL the work i did sometimes HOURS worth of work, and allot can happen in as little as one hour if your an obsessive expansionist as i am. They are SO annoying and they seem to happen to me the most when either A: Notch releases a new version of the game or B: the game is forced to close out. But remember also that this has happened during normal instances as well, not just the game crashing or being forced to close or new version being added.
This has happened at least 10 times to me in the short 2 months i been playing minecraft, and they are TERRIBLY annoying when they happen. Ill save a game, quit, get back on later then i find out that either im in the same spot i was when i saved, but everything I did since several saves back is gone and back to the state it was several saves back, or it will just put me in several saves back entirely position and all losing ALL the work i did sometimes HOURS worth of work, and allot can happen in as little as one hour if your an obsessive expansionist as i am. They are SO annoying and they seem to happen to me the most when either A: Notch releases a new version of the game or B: the game is forced to close out. But remember also that this has happened during normal instances as well, not just the game crashing or being forced to close or new version being added.