error message and backtrace thrown starting irb

$j -vS irb
jruby 1.7.0.dev (ruby-1.8.7-p357) (2012-04-10 36a6987) (Java HotSpot(TM) Client VM 1.6.0_26) [Windows 7-x86-java]
[ERROR] Terminal initialization failed; falling back to unsupportedjava.lang.NoClassDefFoundError: Could not initialize class org.fusesource.jansi.internal.Kernel32
at org.fusesource.jansi.internal.WindowsSupport.getConsoleMode(WindowsSupport.java:50)
at jline.WindowsTerminal.getConsoleMode(WindowsTerminal.java:176)
at jline.WindowsTerminal.init(WindowsTerminal.java:80)
at jline.TerminalFactory.create(TerminalFactory.java:93)
at jline.TerminalFactory.get(TerminalFactory.java:151)
at jline.console.ConsoleReader.<init>(ConsoleReader.java:197)
at jline.console.ConsoleReader.<init>(ConsoleReader.java:177)
at org.jruby.ext.Readline.initReadline(Readline.java:106)
at org.jruby.ext.Readline.s_readline(Readline.java:164)
at org.jruby.ext.Readline$INVOKER$s$s_readline.call(Readline$INVOKER$s$s_readline.gen)
at org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:332)
at org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:203)

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