See 2 Candidates Question Vote In Pr. George’s in the Washington Post and Major Ignored Election Issue by Lisa Handley writing at Maryland Politics Watch. Lisa writes about problems with the mixing of provisional ballots cast because of machine malfunction versus provisional ballots cast for other reasons (e.g., a person claims to be registered but is not listed in the voter rolls for that location). I spoke to a reporter about this issue on election day, and it was clear even then that this was going to be a mess in the event of an election close enough to be decided by provisional ballots.