Final Cut Pro Won't Open Without Loading Crashes That Necessitate A Computer Restart

I've been using FCPx for years. I just recently, after having made projects for four years on my current computer noticed FCP acting up. The project I was working on wouldn't allow me to view the content when played, it would skip through and then freeze up. It did this with all media added regardless of format. It would then remain frozen with no hope of recovery. So I'd have to quit FCP. Then I'd attempt to restart it and it wouldn't restart, it would get stuck like that and I had to restart the entire computer to quell the issue. Then the process began again. I've spent all day today removing the bulk of the library I'd had on it (amounting to around 200 GB's of memory) so that it's basically down to one library with barely any backup etc. I figured this would solve the issue, yet today as I attempted to add mov. files to the project once again the same problem came up. It wouldn't play the content when prompted and when I paused it to scrub back to what I needed to watch, it froze, acted like it was loading and had to be forced to quit. Now, once again it won't open so I will need to restart my computer again to have it come up. I reset my preferences at one point before this began to solve a previous issue. I don't know if doing that again is advised. . . I also restarted the program and computer after making changes to the library size and skimming it down to nothing so it had time to reset but it doesn't look like that's working. Honestly I've never had this many issues and I'm not sure where this is coming from all of the sudden. I had no problems making projects of similar style, length and content a month ago. Looking for any sort of guidance as I'm now going to be behind on my work. . . hoping to have this fixed as soon as possible.

I'm running an older version of Mac OS so I can't update the program. Other stats available upon request.