Urgent help with crashing problem

[BCXtreme]

Hello everyone,

Okay, so I was playing around in creative mode, and I middle-clicked a Wireless Transmitter, which apparently has the unintended side-effect of murdering the entire level. The game crashed immediately, and now it crashes immediately any time I try to load the world. I tried removing the offending Wireless Transmitter from my inventory via NBTExplorer, but it didn't fix the problem. It's been a while since I did my last backup, and I really don't want to lose that much work. Is there any way I can fix this problem? Would the crash log be beneficial? (I couldn't find anything remotely helpful in there.)