javascript error: element has no properties

[freemarket]

Hi,

Error text from firebug under FF 2.0.12:

http://XXXXXXXXX.com:8091/charms-dev/a4j_3_2_0-SNAPSHOTorg.ajax4jsf.javascript.PrototypeScript.jsf
Line 220
element has no properties
stopObserving(null, "mousedown", function(), false)a4j_3_2_0-SNAPSHO... (line 220)
stopObserving("mainform:insertedPage:editRecPanelHeader", "mousedown", function(), undefined)scrollable-data-t... (line 74)
show()modalPanelBorders... (line 3)
destroy()modalPanel.js.jsf (line 36)
onafterajax(Object _query=Object _documentElement=html options=Object, Object type=click target=a#mainform:link_Create, undefined)modalPanel.js.jsf (line 22)
processResponse(Object _query=Object _documentElement=html options=Object)a4j_3_2_0-SNAPSHO... (line 77)
getParseErrorText()a4j_3_2_0-SNAPSHO... (line 22)
[Break on this error] name='keydown';if(element.removeEventListener){element.removeEventListener(name,...

Context is form with a4j:commandButton with oncomplete within dynamically included page under partial page navigation:

<h:panelGrid columns="2">
 <a4j:commandButton id="edit_rec" actionListener="#{dBCrudBean.actionSave}" value="Save" immediate="true" oncomplete="javascript:Richfaces.showModalPanel('editRecPanel')">
 <a4j:actionparam name="insertModeText" value="false" assignTo="#{dBCrudBean.insertModeText}"/>
 </a4j:commandButton>
 <a4j:commandButton id="clearedit_rec" type="reset" value="Reset"/>
 </h:panelGrid>

I simply navigate away from this page using navigation links on left-hand side div and go to another form. The editRecPanelHeader refers to this modalPanel defined in another .xhtml:

<rich:modalPanel autosized="true" id="editRecPanel">
 <f:facet name="header">
 <h:outputText value="Record Updated"/>
 </f:facet>

Is there anything explicit that needs to be done to deactivate the event waiting on the oncomplete which is never completed to prevent this javascript error from firing?

This project has the following jars:

activation.jar
commons-beanutils-core.jar
commons-collections-3.2.jar
commons-dbcp-1.2.2.jar
commons-digester-1.8.jar
commons-logging-1.1.jar
commons-pool-1.3.jar
ibatis-common-2.jar
ibatis-dao-2.jar
ibatis-sqlmap-2.jar
jhighlight-1.0.jar
jsf-api-1.2_04-p02.jar
jsf-facelets.jar
jsf-impl-1.2_04-p02.jar
log4j-1.2.15.jar
mail.jar
nekohtml-0.9.5.jar
ojdbc14.jar
phaseTracker.jar
richfaces-api-3.2.0-SNAPSHOT.jar
richfaces-impl-3.2.0-SNAPSHOT.jar
richfaces-ui-3.2.0-SNAPSHOT.jar
xercesImpl-2.4.0.jar

Regards,
Henry