What build of MC13 are you using? If not 13.0.171, try updating.
We've seen some bad MP3 files in the last two or three months. Files with a megabyte of null characters at the beginning, for example.
See if you can isolate which files cause the problem.
I am using 13.0.171
I couldn't find which files cause the problem because after the crash I continued to analyze the audio (not repeating what is already done) and the files passed (took me several crashes though)
I am using mp3tag 2.43, and dbpoweramp shell integration 13.1 to verify that the mp3gain didn't spoil the files and it looks ok.
Both MC13 and mp3gain are sensitive to the path+file name so if somewhere there are chars like
"Mon
טmouvant amour" the file won't be dragged to mp3gain. also MC13 will fail trying to "clean" the tag ( it will say that the file either not exist or read only...)
when the crash happens I saw in the report there is a large section of stack info.
by the way there is a cosmetic bug in the audio analysis: when you set for 4 files at once upon ending when there are less then 4 files to complete the counter shows "X-4" finished. when all finished the counter fix itself.