Server Crash when User Joins on 1.8.6

The server crashes when I join from within my local network, and when other users join from outside networks. In some cases, the world will appear to render for an instant - and in other cases not at all - before the server crashes. Seems to be affecting all versions of Minecraft Server from 1.8.6 back to 1.8.2. Server 1.8.1 worked. Here is the crash report:

---- Minecraft Crash Report ----
// Don't do that.

Time: 6/3/15 10:06 PM
Description: Exception in server tick loop

java.lang.UnsatisfiedLinkError: Can't obtain static newInstance method for class com.sun.jna.Structure
	at com.sun.jna.Native.initIDs(Native Method)
	at com.sun.jna.Native.<clinit>(Native.java:135)
	at com.sun.jna.Pointer.<clinit>(Pointer.java:42)
	at com.sun.jna.platform.win32.WinReg$HKEY.<init>(WinReg.java:32)
	at com.sun.jna.platform.win32.WinReg.<clinit>(WinReg.java:61)
	at oshi.software.os.windows.WindowsHardwareAbstractionLayer.getProcessors(WindowsHardwareAbstractionLayer.java:33)
	at g.<clinit>(SourceFile:16)
	at net.minecraft.server.MinecraftServer.B(SourceFile:579)
	at ko.B(SourceFile:299)
	at net.minecraft.server.MinecraftServer.A(SourceFile:535)
	at net.minecraft.server.MinecraftServer.run(SourceFile:451)
	at java.lang.Thread.run(Unknown Source)