Disappearing Blocks?

[garlvinland1 0]

So I've gotten permissions for building/destruction in a pretty nice, unused area, and I've been doing well in building up a wood supply. I took a trip to a nearby city at the end of one day, and logged off there. I get on today, roughly two days have passed, and return to my plot to find that a bunch of the trees are floating. I realized that the cause of this was that several layers of earth had been sheared out from under them. I don't know if this was a result of either a world-saving issue or just a passing griefer, and it's not much of an issue yet since it was only dirt, but I loathe to think of what would happen if this repeats after something important, like a redstone machine, has been built. I wanted to post screenshots of the area, but the site won't let me. If requested, I can offer co-ordinates for staff to visit the location.

[Daisy 9735]

This players questions have been answered and the situation resolved. Should you wish to have this reopened, please PM me your reasons why it should be so.