Yes, I do believe the spirit lives on, and especially the spirit of your son. Do you really think it was totally accidental that you came across that chip? Maybe, in some way he is reaching out to you to help you to remember the times he was sober and not just the pain of his loss and the way he died. He probably never meant to do that and left before he could say goodbye. I hope that you can find the healing that comes from forgiveness, which I'm sure is what he'd want to. I will send prayers of strength and serenity your way.