#25 Frozen on splash screen

[NGC3034]

Hello. Stuck while loading.
mindraider 2011-12-24: 8.0
Ubuntu 18.04.1 LTS Linux version 4.15.0-45-generic
OpenJDK Runtime Environment (build 1.8.0_191-8u191-b12-2ubuntu0.18.04.1-b12)
OpenJDK 64-Bit Server VM (build 25.191-b12, mixed mode)

log4j:WARN No appenders could be found for logger (com.mindcognition.mindraider.MindRaiderApplication).
log4j:WARN Please initialize the log4j system properly.
...
Exception in thread "main" [Loaded java.lang.Throwable$PrintStreamOrWriter from /usr/lib/jvm/java-8-openjdk-amd64/jre/lib/rt.jar]
[Loaded java.lang.Throwable$WrappedPrintStream from /usr/lib/jvm/java-8-openjdk-amd64/jre/lib/rt.jar]
java.lang.IllegalStateException: This function should be called while holding treeLock
    at java.awt.Component.checkTreeLock(Component.java:1201)
    at java.awt.Container.validateTree(Container.java:1692)
    at com.mindcognition.mindraider.ui.swing.explorer.ExplorerJPanel.<init>(ExplorerJPanel.java:131)
    at com.mindcognition.mindraider.ui.swing.explorer.ExplorerJPanel.getInstance(ExplorerJPanel.java:136)
    at com.emental.mindraider.ui.frames.MindRaiderMainWindow.<init>(MindRaiderMainWindow.java:171)
    at com.emental.mindraider.ui.frames.MindRaiderMainWindow.getInstance(MindRaiderMainWindow.java:120)
    at com.mindcognition.mindraider.MindRaiderApplication.main(MindRaiderApplication.java:237)
    at MindRaiderRunner.main(MindRaiderRunner.java:53)