Erro Exception in thread "Timer-0"

pessoal , após incluir as configurações do C3p0 , de tempos em tempos aparece o seguinte erro

[color=red]

GRAVE: Exception in thread “Timer-0” [/color]

GRAVE: java.lang.IllegalStateException: WEB9031: WebappClassLoader unable to load resource [com.mchange.v2.io.IndentedWriter], because it has not yet been started, or was already stopped

at org.glassfish.web.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1411)

at org.glassfish.web.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1369)

at com.mchange.v2.async.ThreadPoolAsynchronousRunner.getMultiLineStatusString(ThreadPoolAsynchronousRunner.java:281)

at com.mchange.v2.async.ThreadPoolAsynchronousRunner.access$100(ThreadPoolAsynchronousRunner.java:36)

at com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector.run(ThreadPoolAsynchronousRunner.java:616)

at java.util.TimerThread.mainLoop(Timer.java:512)

at java.util.TimerThread.run(Timer.java:462)