I sent Ed-e back to Primm and when I went there later he wasn't there. I even looked back at the spot and surrounding area (cottonwood cove) where I released him and I still can't find him. Have I fallen into yet another irreversible fallout glitch and my poor robot is forever lost to digital oblivion?

This site is the best for all your fallout needs, enjoy :) http://fallout.wikia.com/wiki/Fallout_Wiki

Companions will wait for you to retrieve them in your presidential suite in the Lucky 38