Internal Server Error

[Photo Frog]

Every time I try to join a specific server it doesn't work, sometimes it loads for a second but it always says "Internal Server Error" I don't know whats going on, I've reset the pack, uninstalled the launcher un and re installed java and restarted my computer, any help would be much apriciated

[Kalbintion]

post the issue on the tracker. the link to the tracker (and the tracker guidelines) is available in my signature below. make sure to include a client log and a server log.