Cannot send chat message or move bukkit

Hey guys so idk if this is the right forum to post this in but i just really need help :/ this happens a lot to all my players not just me we get this message in chat every time we try sending a message that says "cannot send chat message" and then when we move we get tped back to the spot we where standing on before we move, we go invisible on the server but we still are online on the tab basically you become a ghost who cannot move Please help

 

what version of bukkit and what plugins do you have installed? Do players have the proper permissions?

 

@timtower what do you mean like essenentials ?

 

I think it is a login plugin for cracked servers.
Can you do /register or /login or something else?

 

@MrGussio nope

@timtower I don't think we have any login plugins then but I figured something else out, this only occurs if you are near another player.. Don't know if this hint can help out :/

EDIT by Moderator: merged posts, please use the edit button instead of double posting.