Weird thing happened: People without OP can't build in a specified zone

IDK why my server had a chunk error, I fixed it with a plugin called Chunkster... The console haven't gave me any error anymore... But now the players can't build things at the spawn of the server! (The most important zone of the server), if they move some blocks away they can... even it happens with admins, moderators... ONLY OPS CAN BUILD THINS. I tried removing all the plugins and it's the same, I tryed removing the players of the /players file of the world and its the same...

Anyone knows why does this happen?

EDIT: It got fixed simply changing to 0 the spawn-radius of the bukkit.yml file, I have been like 1 month using this server and this only happened today... weird!