@lschmidt could you tell us a bit more on how this kind of crashes happen? What kind of action are you performing when it crashes? (CAD modeling, setting up a simulation, postprocessing, etc...) The more information you can share the better. Also, which version of Sim4Life are you using? (you can see that by clicking Help -> About in the main menu)
As for recovering the project's state when the software crashes, you can check in the project's folder (where
myproject.smash, say, is located) to see if there are other files with names like
myproject.smash.d7311d14-6e21-4ec7-9ca8-99ec2da7ca69 and rename them to something like
myproject_backup.smash so that you can open them in Sim4Life. One of these files (usually the one with the latest modification timestamp) should contain the latest modifications you made to the project. This might or might not work, but it's often worth a try.