Maybe the best way to fix this is to delete everything in the MAY folder in appdata-roaming, back up the wallet.dat first. Delete everything except for the wallet.dat and let the wallet re-sync from the start again. It might take a couple of hours but hopefully this fixes your issue as I have also had this issue in the past with MAY but that was caused to the power going out which then gave me an error so I just re-synced it from the start and all was well again. Remember to not delete the wallet.dat file or you will lose your coins and be sure to back up the wallet.dat before deleting anything. Good luck!