This is a great example of what happens when the government says that felony=no guns without respect to the circumstances. What happens when they decide it's a felony to drive over 55mph? When they decide it's a felony to use foul language?
DISABLING OF RIGHTS WITHOUT SPECIFIC DUE PROCESS IS BS!
In any case; I think you will have to get in touch with your governor. I believe the procedure is something like "petition for restoration of rights" and I believe the governor has sole discretion on whether to expunge this from your record or restore the rights.
Someone else who knows more about this may come along and lend some insight.