Blend 4 crashes again!

i cant seem build project @ in blend anymore, vs2010 works fine, when try build blend following error:

im sick of blend crashing time, cant work time critical when crashes time. please help.

microsoft® expression® crash report:

date: 2011-01-27 14-12-26


application version: 4.0.1000.1000
operating system version: microsoft windows nt 6.1.7600.0
common language runtime version: 4.0.30319.1

system.nullreferenceexception: object reference not set instance of object.
   @ microsoft.expression.designmodel.markup.xamlparser.getpropertyvaluetextcontenttype(itype valuetype)
   @ microsoft.expression.designmodel.markup.xamlparser.addpropertiesandchildren(xamlparsercontext parsercontext, documentcompositenodereference nodereference, xmlelementreference xmlelementreference, xmlelement xmlelement, predicate`1 propertyfilter)
   @ microsoft.expression.designmodel.markup.xamlparser.addpropertiesandchildren(xamlparsercontext parsercontext, documentcompositenodereference nodereference, xmlelementreference xmlelementreference, xmlelement xmlelement)
   @ microsoft.expression.designmodel.markup.xamlparser.parsecompositeelement(xamlparsercontext parsercontext, idocumentnodereference nodereference, itype typeid, xmlelementreference xmlelementreference, xmlelement xmlelement)
   @ microsoft.expression.designmodel.markup.xamlparser.parseelementcontent(xamlparsercontext parsercontext, idocumentnodereference nodereference, itype typeid, xmlelementreference xmlelementreference, xmlelement xmlelement)
   @ microsoft.expression.designmodel.markup.xamlparser.parseelement(xamlparsercontext parsercontext, idocumentnodereference nodereference, xmlelementreference xmlelementreference, xmlelement xmlelement, documentnode& node)
   @ microsoft.expression.designmodel.markup.xamlparser.parsecontent(xamlparsercontext parsercontext, idocumentnodereference nodereference, xmlelementreference xmlelementreference, xmlelement xmlelement, iproperty childproperty, typeconverter texttypeconverter, itypeid texttype, propertyhandling propertyhandling)
   @ microsoft.expression.designmodel.markup.xamlparser.addpropertiesandchildren(xamlparsercontext parsercontext, documentcompositenodereference nodereference, xmlelementreference xmlelementreference, xmlelement xmlelement, predicate`1 propertyfilter)
   @ microsoft.expression.designmodel.markup.xamlparser.addpropertiesandchildren(xamlparsercontext parsercontext, documentcompositenodereference nodereference, xmlelementreference xmlelementreference, xmlelement xmlelement)
   @ microsoft.expression.designmodel.markup.xamlparser.parsecompositeelement(xamlparsercontext parsercontext, idocumentnodereference nodereference, itype typeid, xmlelementreference xmlelementreference, xmlelement xmlelement)
   @ microsoft.expression.designmodel.markup.xamlparser.parseelementcontent(xamlparsercontext parsercontext, idocumentnodereference nodereference, itype typeid, xmlelementreference xmlelementreference, xmlelement xmlelement)
   @ microsoft.expression.designmodel.markup.xamlparser.parserootelement(xamlparsercontext parsercontext, xmlelementreference xmlelementreference, xmlelement xmlelement)
   @ microsoft.expression.designmodel.markup.xamlparser.parse(xamlparsercontext parsercontext, xmldocumentreference xmldocumentreference, xmldocument xmldocument)
   @ microsoft.expression.designmodel.markup.xamlparser.parseinternal(xamlparsercontext parsercontext)
   @ microsoft.expression.designmodel.markup.xamldocument..ctor(idocumentcontext documentcontext, itypeid expectedroottype, itextbuffer textbuffer, encoding documentencoding, ixamlserializerfilter defaultxamlserializerfilter)
   @ microsoft.expression.designsurface.documents.scenexamldocument..ctor(idocumentcontext documentcontext, iundoservice undoservice, itypeid expectedroottype, itextbuffer textbuffer, encoding documentencoding)
   @ microsoft.expression.designsurface.documents.xamldocumenttype.createdocument(iproject project, iprojectitem projectitem, itextbuffer textbuffer, boolean isreadonly, encoding encoding)
   @ microsoft.expression.designsurface.documents.xamldocumenttype.createdocument(iproject project, iprojectitem projectitem, string contents, boolean isreadonly, encoding encoding)
   @ microsoft.expression.designsurface.documents.xamldocumenttype.opendocument(iprojectitem projectitem, iproject project, boolean isreadonly)
   @ microsoft.expression.project.projectitem.opendocument(boolean isreadonly, boolean suppressui)
   @ microsoft.expression.project.projectitembase.opendocument(boolean isreadonly)
   @ microsoft.expression.designsurface.documents.projectxamlcontext.openprojectdocument(iprojectitem projectitem)
   @ microsoft.expression.designsurface.documents.projectxamlcontext.opendocument(string path)
   @ microsoft.expression.designsurface.documentprocessors.documentprocessor.work()
   @ microsoft.expression.framework.asyncprocess.dowork(object sender, doworkeventargs e)
   @ microsoft.expression.designsurface.documentprocessors.synchronousasyncmechanism.begin()
   @ microsoft.expression.framework.asyncprocess.begin()
   @ microsoft.expression.designsurface.documentprocessors.statenamereferenceverifier.verify(documentnode node)
   @ microsoft.expression.designsurface.documentprocessors.referenceverifierprocessor.processdocument(scenedocument document)
   @ microsoft.expression.designsurface.documentprocessors.documentprocessor.work()
   @ microsoft.expression.framework.asyncprocess.dowork(object sender, doworkeventargs e)
   @ microsoft.expression.framework.currentdispatcherasyncmechanism.ondowork(object argument)
   @ system.windows.threading.exceptionwrapper.internalrealcall(delegate callback, object args, int32 numargs)
   @ ms.internal.threading.exceptionfilterhelper.trycatchwhen(object source, delegate method, object args, int32 numargs, delegate catchhandler)
   @ system.windows.threading.dispatcheroperation.invokeimpl()
   @ system.windows.threading.dispatcheroperation.invokeinsecuritycontext(object state)
   @ system.threading.executioncontext.runtrycode(object userdata)
   @ system.runtime.compilerservices.runtimehelpers.executecodewithguaranteedcleanup(trycode code, cleanupcode backoutcode, object userdata)
   @ system.threading.executioncontext.runinternal(executioncontext executioncontext, contextcallback callback, object state)
   @ system.threading.executioncontext.run(executioncontext executioncontext, contextcallback callback, object state, boolean ignoresyncctx)
   @ system.threading.executioncontext.run(executioncontext executioncontext, contextcallback callback, object state)
   @ system.windows.threading.dispatcheroperation.invoke()
   @ system.windows.threading.dispatcher.processqueue()
   @ system.windows.threading.dispatcher.wndprochook(intptr hwnd, int32 msg, intptr wparam, intptr lparam, boolean& handled)
   @ ms.win32.hwndwrapper.wndproc(intptr hwnd, int32 msg, intptr wparam, intptr lparam, boolean& handled)
   @ ms.win32.hwndsubclass.dispatchercallbackoperation(object o)
   @ system.windows.threading.exceptionwrapper.internalrealcall(delegate callback, object args, int32 numargs)
   @ ms.internal.threading.exceptionfilterhelper.trycatchwhen(object source, delegate method, object args, int32 numargs, delegate catchhandler)
   @ system.windows.threading.dispatcher.invokeimpl(dispatcherpriority priority, timespan timeout, delegate method, object args, int32 numargs)
   @ ms.win32.hwndsubclass.subclasswndproc(intptr hwnd, int32 msg, intptr wparam, intptr lparam)
   @ ms.win32.unsafenativemethods.dispatchmessage(msg& msg)
   @ system.windows.threading.dispatcher.pushframeimpl(dispatcherframe frame)
   @ system.windows.threading.dispatcher.pushframe(dispatcherframe frame)
   @ system.windows.threading.dispatcher.run()
   @ system.windows.application.rundispatcher(object ignore)
   @ system.windows.application.runinternal(window window)
   @ system.windows.application.run(window window)
   @ system.windows.application.run()
   @ microsoft.expression.framework.expressionapplication.runapplication()
   @ microsoft.expression.application.main(string[] args)

nothing? no 1 know here?

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