Memory problems

[Tyler]

Hey guys, just had a question for you. Sometimes I'll save in Halo (Save last checkpoint) and when I go to play the game the next day the game starts a couple of checkpoints back from where I saved. Has anyone experienced this problem? I'm sure I'm not pressing the wrong buttons when saving. Also I have games saved (i do presently) on the hard drive as well as music, but it still says I have 50000 blocks beside both Total Memory and Available memory. So according to my Xbox there is nothing on the hard drive, but in reality there is. There should be about 600 blocks used but it doesn't show this! What's the deal?
Thanks in advance, Tyler.

[Bundy]

If you look again it says 50,000+ blocks free.