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)