SWT designer 出错的问题

SWT designer 出错，每次首次编辑都可，突然就会出错，错误信息如下，望帮助看一下什么原因？Plug-in Provider: Instantiations
Plug-in Name: WindowBuilder Professional
Plug-in ID: com.swtdesigner
Plug-in Version: 6.9.0.200901260232java.lang.NullPointerException
    at com.swtdesigner.model.swt.widgets.menu.factory.MenuObjectInfoParserFactory.create(MenuObjectInfoParserFactory.java:43)
    at com.swtdesigner.model.parser.factory.JavaInfoFactory.create(JavaInfoFactory.java:114)
    at com.swtdesigner.model.parser.factory.JavaInfoFactory.create(JavaInfoFactory.java:97)
    at com.swtdesigner.model.parser.factory.JavaInfoFactory.create(JavaInfoFactory.java:90)
    at com.swtdesigner.model.parser.JavaInfoParser$ParserVisitor.endVisit(JavaInfoParser.java:1458)
    at org.eclipse.jdt.core.dom.ClassInstanceCreation.accept0(ClassInstanceCreation.java:337)
    at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2478)
    at org.eclipse.jdt.core.dom.ASTNode.acceptChild(ASTNode.java:2525)
    at org.eclipse.jdt.core.dom.VariableDeclarationFragment.accept0(VariableDeclarationFragment.java:225)
......Full stack trace (to see full context):
org.apache.commons.lang.exception.NestableError: java.lang.NullPointerException
    at com.swtdesigner.model.parser.factory.JavaInfoFactory.create(JavaInfoFactory.java:120)
    at com.swtdesigner.model.parser.factory.JavaInfoFactory.create(JavaInfoFactory.java:97)
    at com.swtdesigner.model.parser.factory.JavaInfoFactory.create(JavaInfoFactory.java:90)
    at com.swtdesigner.model.parser.JavaInfoParser$ParserVisitor.endVisit(JavaInfoParser.java:1458)
    at org.eclipse.jdt.core.dom.ClassInstanceCreation.accept0(ClassInstanceCreation.java:337)
    at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2478)
    at org.eclipse.jdt.core.dom.ASTNode.acceptChild(ASTNode.java:2525)
    at org.eclipse.jdt.core.dom.VariableDeclarationFragment.accept0(VariableDeclarationFragment.java:225)
    at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2478)
    at org.eclipse.jdt.core.dom.ASTNode.acceptChildren(ASTNode.java:2548)
    at org.eclipse.jdt.core.dom.VariableDeclarationStatement.accept0(VariableDeclarationStatement.java:273)
    at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2478)
    at org.eclipse.jdt.core.dom.ASTNode.acceptChildren(ASTNode.java:2548)
    at org.eclipse.jdt.core.dom.Block.accept0(Block.java:136)
    at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2478)
 ....Caused by: java.lang.NullPointerException
    at com.swtdesigner.model.swt.widgets.menu.factory.MenuObjectInfoParserFactory.create(MenuObjectInfoParserFactory.java:43)
    at com.swtdesigner.model.parser.factory.JavaInfoFactory.create(JavaInfoFactory.java:114)
    ... 52 moreDesigner Configuration Details:Product: WindowBuilder Professional
Version: 6.9.0.200901260232
Expected: Eclipse 3.4
Actual: Eclipse 3.4.0.v20080512
Actual Eclipse Build Name: 
Actual Eclipse Build ID: M20080709-0800
IDE Actual Name: Eclipse
IDE Actual Version: 3.3.101.v200809111700
IDE Actual NL: zh_CN
Serial Number: WindowBuilderPro-204772830
Activation Key: WindowBuilderPro-YE21G-SM09K9QT4X
Physical Address: 00-E0-4D-6F-ED-08
Code Gen: Flat Mode, Use Existing, First Assignment, Make Final
Events: Anonymous Class
Platform Product: Eclipse
Platform Version: 3.3.101.v200809111700
OS Name: Windows XP
OS Architecture: x86
OS Version: 5.1