Random parts of map on MC server dissapear/reset

I'm furious with what just happened, the (Bukkit) server I'm working on deleted almost half of something I spent hours building. Does anyone have any clue what could have caused this? I logged off and everything was fine, restarted the server, then when I logged back on it was just gone.

Note: Whatever happened didn't just take a chunk out of my beautiful Isengard, it also rewinded a spawn area I was working on by several hours. It wasnt cut in half, just alot of progress lost.

Could this be caused by my internet's DNS acting up and my connection to the server being faulty? I'm constantly having DNS issues...

Plugins

• factions
• essentials
• godpowers
• mcmmo
• trade
• worldedit
• worldguard