Forum:Not Enough Items just disappeared mid-game?

So I was playing on my SMP server today, everything running just fine, when all of a sudden, Not Enough Items just... disappeared. It just vanished. It doesn't show up in my single player worlds either. I checked the files and the mod files are still there... everyone else on the server still sees it.Where did mine go? WHat could cause this? Any advice would be much appreciated.