请教高手解决一下这个异常，用poi操作excel的.xls没问题，.xlsx有问题
Exception in thread "AWT-EventQueue-0" org.apache.xmlbeans.impl.values.XmlValueD
isconnectedException
  at org.apache.xmlbeans.impl.values.XmlObjectBase.check_orphaned(XmlObjec
tBase.java:1213)
  at org.apache.xmlbeans.impl.values.XmlObjectBase.newCursor(XmlObjectBase
.java:243)
  at org.apache.xmlbeans.impl.values.XmlComplexContentImpl.arraySetterHelp
er(XmlComplexContentImpl.java:1073)
  at org.openxmlformats.schemas.spreadsheetml.x2006.main.impl.CTFontsImpl.
setFontArray(Unknown Source)
  at org.apache.poi.xssf.model.StylesTable.writeTo(StylesTable.java:385)
  at org.apache.poi.xssf.model.StylesTable.commit(StylesTable.java:443)
  at org.apache.poi.POIXMLDocumentPart.onSave(POIXMLDocumentPart.java:329)

  at org.apache.poi.POIXMLDocumentPart.onSave(POIXMLDocumentPart.java:333)

  at org.apache.poi.POIXMLDocument.write(POIXMLDocument.java:173)
  at NetSchoolFrame$CanvasSaveButtonHandler.actionPerformed(NetSchool.java
:1284)
  at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:20
18)
  at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.jav
a:2341)
  at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel
.java:402)
  at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259
)
  at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonL
istener.java:252)
  at java.awt.Component.processMouseEvent(Component.java:6504)
  at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
  at java.awt.Component.processEvent(Component.java:6269)
  at java.awt.Container.processEvent(Container.java:2229)
  at java.awt.Component.dispatchEventImpl(Component.java:4860)
  at java.awt.Container.dispatchEventImpl(Container.java:2287)
  at java.awt.Component.dispatchEvent(Component.java:4686)
  at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832
)
  at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)

  at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
  at java.awt.Container.dispatchEventImpl(Container.java:2273)
  at java.awt.Window.dispatchEventImpl(Window.java:2713)
  at java.awt.Component.dispatchEvent(Component.java:4686)
  at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
  at java.awt.EventQueue.access$000(EventQueue.java:101)
  at java.awt.EventQueue$3.run(EventQueue.java:666)
  at java.awt.EventQueue$3.run(EventQueue.java:664)
  at java.security.AccessController.doPrivileged(Native Method)
  at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDo
main.java:76)
  at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDo
main.java:87)
  at java.awt.EventQueue$4.run(EventQueue.java:680)
  at java.awt.EventQueue$4.run(EventQueue.java:678)
  at java.security.AccessController.doPrivileged(Native Method)
  at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDo
main.java:76)
  at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
  at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThre
ad.java:211)
  at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.
java:128)
  at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre