Solved Players have access to OP commands despite no one being made an OP

i just checked my server as i run it from home, and i noticed that some random players had joined, and somehow gained access to OP commands, mostly so far by forcing the server to save but i fear this could have repurcussions if they somehow grab a hold of changing gamemodes and whatnot.

im using the developmental build of 1.5.1, as far as im concerned no one has been made an OP, not even myself, is there anything i can do to prevent this kind of thing?? while something such as /save-all might not be too detrimental, i'd rather not have players being able to tinker with my server at their will.

any way to prevent this or fix it?

 

redownload all plugins from dev.bukkit.org only.

 

thats the thing, i dont have any plugins, its just the vanilla bukkit server.

i also only ever get plugins from the dev.bukkit.org if i ever need them.

 

people shouldnt have any access to /op without being op.
clean up your ops.txt and make sure online mode is set to true.