Hi,
Im not sure if this is helpfull, but this is what i just got when i was first playing in my single server, logged out because it kept freezing (message no responce), than becaus the game menu was blinking i pressed the litle x
and got this pop-up. 
Windows 7 (x64) 6.1 Java: 1.8.0_131 amd64 0.9.2.1_37 -H:3072 -D:3072 (Steam)
Intel(R) Core(TM) i5-4460 CPU @ 3.20GHz, H97-PLUS, 8134 MB (3186 MB Heap)
NVIDIA GeForce GT 730 20150527000000.000000-000 9.18.13.5306
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Error occurred during application-update (25)
java.lang.IllegalStateException: RefreshFlags invalid for spatial Gui Node: 2
RF_LIGHTLIST: false
RF_CHILD_LIGHTLIST: false
RF_TRANSFORM: false
RF_BOUND: true
RF_MATPARAM_OVERRIDE: false
at com.jme3.scene.Spatial.checkCulling(Spatial.java:360)
at commons.c.a(SourceFile:538)
at commons.c.renderScene(SourceFile:533)
at commons.c.renderViewPort(SourceFile:644)
at commons.c.a(SourceFile:704)
at commons.c.render(SourceFile:685)
at commons.JIWApplication.update(SourceFile:343)
at com.jme3.system.lwjgl.LwjglAbstractDisplay.runLoop(LwjglAbstractDisplay.java:151)
at com.jme3.system.lwjgl.LwjglDisplay.runLoop(LwjglDisplay.java:198)
at com.jme3.system.lwjgl.LwjglAbstractDisplay.run(LwjglAbstractDisplay.java:232)
at java.lang.Thread.run(Unknown Source)
