Mysterious rollback bug?

I'm not sure if this is the right area to post this, but i'm hoping to receive some solutions.

So everytime I, or any of my players log out, we roll back to a certain point. It's the same point everytime we re-log as well.

So could anyone give me an idea as to what the problem could be. I'm also quite new to running a server, but quite a few people play this and i don't want to keep them in the dark about the situation. (Approximately 20-30 online at a time)

Thanks everyone,

-Embryo