FCP X Libraries get corrupted, FCP X crashes on launch

I've been running into this consistent issue recently and it has become extremely frustrating.

I create new libraries for different sets of projects and events as a matter of course. The original libraries are stored on a Firewire attached Drobo. The backups go to the Movies directory on the boot drive.

I will be working on a project and complete the work and then export it, typically direct to Vimeo, but sometimes to a master file. Then I will exit FCP X and when I come back, one or more of the events/projects will show the yellow caution symbol and in short order FCP X will crash hard. I have tried repairing the libraries using the Digital Rebellion tools and used it's Crash Analyzer. It told me I had font issues so I used Font Book to remove the duplicates, and cleaned the font cache.

All to no avail. The original clips are ok in the event packages so I could do the projects again, but that is a major pain in the butt, particularly when everything was working. The videos are very simple, there is a placed MP4 intro, the video clips themselves using basic video and audio edits keyed over a still image, then an FCP X created credits sheet. Hardly anything of significance.

I would like to understand several things.

1. Why is a project/event ok until I quit FCP X and then bad when I reopen?

2. Why are the automatic backups also showing as bad when I try to reopen?

3. Since most videos use all the same editing tools, the same intro and the same end slate, why are some bad and others not?

4. What can I do to prevent this from continuing to happen? This machine is kept up to date and I am running the most current FCP X available 10.2.1 Build 264102

5. Are there any known issues with Canon's XF Plugin for Final Cut Pro X? Most of my stuff is shot on a C300 and run through Canon's XF Utility to create a single contiguous clip stored on disk prior to import to FCP X. I have tried removing this plugin, but the library once messed up stays that way. Since all my footage is in the MXF format, I need the utility to be able to read the files in FCP X don't I?