Colorado Only: If you registered recently, or have a friend who did, see if you are on the list http://www.neweracolorado.org/
If you search on on a county name, you can narrow down the list. e.g. Search on Boulder you get about 1826 names, you can scroll through them and see if you find anyone you know.
If so, go to the clerk and early vote. I have heard that the Boulder County Clerk is clearing these up at early voting but may not be able to do it on Election day.
A backstory on Coffman (GOP Secretary of State) voter suppression is here
I voted already and so did everyone in my house.