For a while I've been "chicken" to remove iRealb/Amazon App from my Nexus. Well, I finally did it. Now, I have iRealb from the Play store and I don't expect any more problems. And I was successfully able to restore all songs from the backup!

Seriously, I wonder if my problem was truly unique or if other users would have the same problem under the same conditions. The trouble came about under these conditions:

1. iRealb purchased from Amazon App store.
2. Whenever an app purchased from the AmazonApp store had an update, my Nexus automatically performed updates. (I had purchased several Apps from Amazon.)
3. When there were App update(s) and I did NOT have internet access, the AmazonApp pop-up thingy would show up when I opened iRealb and I couldn't run iRealb.

I'm optimistic that all will work well now.

Linda - Happy iRealb user