Your switch sounds like it may be experiencing some type of flash corruption. First I would try to reboot the unit and upgrade to the newest firmware on the ADTRAN website if possible. If this does not resolve the issue, try reformatting the flash using Clearing FLASH and Upgrading in AOS Bootstrap.
I went ahead and flagged "Assumed Answered" on this post to make it more visible and help other members of the community find solutions more easily. If you feel like there is a better answer, feel free to come back to this post and select it with the applicable buttons. If you have any additional information on this that others may benefit from, please come back to this post to provide an update. If you still need assistance, we would be more than happy to continue working with you on this - just let us know in a reply.