http://pastebin.com/R4gvtp8J Local Minecraft server log (I copyed the first 1500 lines, but the log are around 18514 lines now)
http://pastebin.com/HYy29DcL ScoutLink Minecraft server log (from the time span where it happen)
https://www.dropbox.com/s/e8h1hd9z1ikg0oj/minecraft_client_bug.png
https://www.dropbox.com/s/ao71fx8fj06dsip/minecraft_client_bug3.png

I'm connected to both my local (CraftBukkit version git-Spigot-ccb601-f92e01b (MC: 1.9.2) (Implementating API version 1.9.2-R0.1-SNAPSHOT)) aswell as minecraft.scoutlink.net server (CraftBukkit version git-Spigot-8a048fe-d8637df (MC: 1.9.4) (Implementing API version 1.9.4-R0.1-SNAPSHOT)).

I'm physicly on both servers. I can see both chats. I can however only move on my local server and only chat there. My screen (game, Minecraft client) blinks all the time, it's like day and night every 0,5 seconds.

How to reproduce: Join an external server but stop it right before the screen changes and you're "inside". Then join the local server.