MP3tag has been crashing when saving tags on "random" files for about the last 3 versions, to the point where it is practically unusable.
I would guess it is probably an unhandled exception when a file is being accessed by another process (Windows Explorer thumbnails, Index Service, Diskeeper, Antivirus, etc).
It is particularly bothersome when saving cover art.
It is happening at least on Windows 8.1 x64 with WMA files.
Every new attempt saving cover art to a set of files leads to a crash on a different file.
Every crash leaves MP3tag in an unusable state and unable to be shutdown forcing the user to logout and log back in.
While we are here re-reporting bugs, I'll re-report another bug that is 100% reproducible and causing data loss: updating a WMA file with MP3tag (for example, adding cover art) results in the Media Created date field being erased.
*** EDITED ***
Spent some time looking into the problem in more depth and have discovered a non-random element.
It looks like it may be that in order for the crash to happen, tags must contain a right-to-left language entry, such as a tag that contains an Arabic name. However, the crash will not always happen with such files, but will often happen on a random file in a set of files that contain such tags.