One of the biggest culprits in project corruption for us was carrying forwards all of our prior Sonar install preferences.
This may be completely voodoo but, it wasn't until we started with a completely fresh install of the of X1 and then patched to expanded that all our problems went away. I loved how fast the feature made the install process and when your working on a deadline, its great. But completely wiping all prior versions of Sonar before the X series and starting from scratch made all the difference.
I know it sucks and its time consuming with all the additional plugs like Dimension Pro but the later installs of Dimension Pro allow you the choice of installing just the VST so you can keep your previous Multisamples directory intact.
And as far as backup,if you have a Gmail account, you already own Google Drive anyway for a cheap online storage option.
Just a thought...