I'm using r111 and have the same problem, auto back up does not mean auto save unfortunately, you need to click save frequently. I've lost a few hours work on two occasions now. It's a real shame construct doesn't have an auto save feature like other programming IDEs or a least save the project each time before preview or export.
Come on guys, I'm going to have to keep bugging you until this feature goes in <img src="smileys/smiley28.gif" border="0" align="middle" />