It happened to me once for now, but this afternoon I plugged 2 USB keys and the application closed again unexpectedly, so maybe there are 2 different locations in your code where handling this event.
I am also pretty sure it did not happened just after inserting them, I think it happened after maybe browsing one of them in a side and the other one in the other side (as my intention was to copy files from one usb key to the other one), I am pretty sure it was before I could F5 the file