Confluence freezes on shutdown with IllegalStateException causing End Program Prompt on Windows

Behaviour:
When closing Confluence on Windows, it freezes with an IllegalStatException that forces an End Program prompt

Expected behaviour:
Confluence should close cleanly

Replication:
To replicate, close any instance of Confluence on Windows

Exception Information:
Exception on mySQL is attached, hSQL exception shown below:

Jan 19, 2007 10:07:52 AM org.apache.coyote.http11.Http11BaseProtocol pause
INFO: Pausing Coyote HTTP/1.1 on http-8080
Exception in thread "AWT-Windows" java.lang.IllegalStateException: Shutdown in p
rogress
at java.lang.Shutdown.add(Shutdown.java:81)
at java.lang.Runtime.addShutdownHook(Runtime.java:190)
at sun.awt.windows.WToolkit.run(WToolkit.java:255)
at java.lang.Thread.run(Thread.java:595)
Exception in thread "HSQLDB Timer @12b9f14" java.lang.NullPointerException
at org.hsqldb.lib.HsqlTimer.nextTask(Unknown Source)
at org.hsqldb.lib.HsqlTimer$TaskRunner.run(Unknown Source)
at java.lang.Thread.run(Thread.java:595)