A mistake in the Z Order bar refresh function caused a lot of random crashes in r120. Oops! We don't normally do updates this close together, but it was a serious issue so we're doing a quick fix. We also have a new automated build system that can deploy a new release to both Steam and the site pretty much with one click, so it's actually relatively painless to do updates like this. Since r120 only came out yesterday and introduces a few new features, check out the r120 changelog if you haven't seen it already.
A few other tweaks and changes have been thrown in. Hopefully this release goes a bit more smoothly!