Whenever I try to log in it says "Security exception met. Connection closed."...I'm not really sure why I'm getting this, it sounds like its trying to say I have some type of hacking tool on my computer? But the only thing I have downloaded since the last time I played are some Minecraft mods.
Try going through your computer, stick-online detects anything malicious, even if its for another game. Just go through your computer and remove anything you think is possible to be hacks or mods Hope you figure it out ;D