Looking at your backtrace report, I would agree that your focus on the Ejector app was appropriate....the report said you had a time-out on the ioKit BlockStorageDriver which is what reads and writes to the HDD / SSD. If the Ejector app didn't "play nice" with that driver, it could very likely be the culprit behind the time-outs that you experienced.
If removing that app has cleared the issue for you (as time will tell), check back here to close the loop with us and send the same info to the app developer to let them know.
