I lost a village once when my hard drive was full -- I didn't realize there was no more space left (another app. was using drive space as virtual memory), so VV couldn't save the game when it quit. When I reopened the game, that slot was empty.

Guessing that this might happen anytime the game can't save when it quits (so for me, no space; for someone else, maybe the folder got deleted, or they don't have permission to write to it, etc.)

Don't know if that helps, since I have a Mac :), but could luck finding your game!

-- Jen