Muse Sounds Spontaneous Deletion

I was working on a score recently, and when trying to add a Violin, I noticed that it had auto-switched to MS Basic. Upon further inspection, Muse Strings, which I have had downloaded since it first released, had spontaneously deleted itself, and I had to re-download it. Afterwards, there was no issue at all, each sound worked just fine. I've never manually deleted a Muse Sounds library, so I'm not sure why exactly this is happening.