After downloading last night’s SDL build, the first two attempts at generating a world crashed the game. Whatever, on the third try it worked, and I continued playing.
Well, twenty minutes later, once I was actually in the game, it crashed again. It wasn’t triggered by crafting or cooking or disassembling anything, it was just as my character was walking around. Needless to say I’m a little nonplussed.
We’ll have to take a look at mapgen. We’re trying to track down what’s happening, but that’s hard when it’s really random.
Important note: Experimentals are sometimes prone to crashing (though we’re getting better and better at preventing them).
We’re actually hot on the trail of the world gen crash, hopefully we’ll at least have an idea of what’s causing it sometime soon.
As for the random crash, said crashes are notoriously difficult to diagnose and fix since without any sort of reliable replication method it’s difficult to determine what the problem was. A reproducible save might help, but without that there isn’t much we can do.
Edit: Dang you Kevin, beating me to the post! 
Also it’s quite likely that it’s the same crash, random walking around crashes are most likely a result of mapgen as well, so crash on startup may be due to the crash-causing thing being in range of the shelter, and random walking around crashes happen when the same thing comes in range when walking.