I would assume the following happened: When the backup was made your harddisk ran out of space, so the backup was incomplete. Then you automatically started the server and when the server tried to add information (probably because of regular housekeeping tasks the game does when it starts up again, or a spawned zombie that destroyed a block, or ...) it couldn't and corrupted the savegame. Just a guess though
Please post the whole logfile to pastebin.com and post a link to it here. Usually a server will start even though a region file is corrupted
@Jugginator See above, there may be another error that prevents startup of this server, but generally, is it possible for the server to not start anymore even though only region files are corrupted? In that case the "regionreset" would be of no help