ADOT officials say the system was operating very slow Thursday morning and that was causing some customers longer-than-normal waits at MVD offices and at authorized third-party offices.
KPHO-TV reports that the MVD's primary call center also was affected.
ADOT worked to identify the source of the slowness, but officials say it appeared to be tied to the mainframe.
Officials say the problem was fixed by noon Thursday and the system was working normally again.
Information from: KPHO-TV, http://www.kpho.com/