Bukkit server map reset after crashing?

Hey guys, tis be BlueDude35. Me and my pal thejay13 are trying to make a Bukkit server called MineVolt. But we always run into this sad, annoying problem. Every time the server crashes, part or all of the map is reset to the original seed. It's been doing this the entire time it's been up. The plugins we have installed are DisguiseCraft, all of the Essentials plugins, Factions, mcMMO, Remote Toolkit, PTweaks, Safe Creeper, SimpleSpleef, Vault, and WorldEdit. Please help :(