If either of you continue to have crashes, you should turn on JRiver logging. See the controls and instructions in MC's menu: Help > Logging
Once that's turned on MC will collect a log continuously. Then, once a crash happens, you go back into the logging menu and "collect log" which will produce a zip file. You can then attach that zip file to a post here, or email it to the developers directly (if they request it).
The MC log file has lots of internal details to help pin down what's going on.
If you are getting crashes during import and/or analysis, the log file will normally tell you the exact file that is causing the crash, as it will be one of the last lines in the log file. This is somewhat common with damaged digital media files. I've seen it dozens of times both in my own collection and in many many reports here.
Good luck to both of you.
Brian.