with the first piece of code you hide the component "R3". It´s now not available and that´s why the second code run into an error.

put a div around "R3" e.g. "Div1" and refresh it.

thanks, but I tried putting DIV tags with an ID around various components on the page, and it get the same result. It will hide the DIV using setRendered and a partial refresh, but when I try to bring it back, the Browser says it cannot find an element with that ID.

You don´t should hide the Div.

Hide "R3" e.g. and refresh the Div.

Ok. Now I understand that. It works fine on other elements on the page (a field, panel, img, etc), but it does not seem to work when trying to put DIV tags around a TR or TD.

If you want to hide fields or somthing else inside a <td> put the whole table into a div and refresh rhe div.

Example table:

<xp:button value="rendered false" id="button5">
        <xp:eventHandler event="onclick" submit="true"
            refreshMode="partial" refreshId="Div2">
            <xp:this.action><![CDATA[#{javascript:getComponent("inputText3").setRendered(false);
}]]></xp:this.action>
        </xp:eventHandler>
    </xp:button>
    <xp:button value="rendered true" id="button6">
        <xp:eventHandler event="onclick" submit="true"
            refreshMode="partial" refreshId="Div2">
            <xp:this.action><![CDATA[#{javascript:getComponent("inputText3").setRendered(true)}]]></xp:this.action>
        </xp:eventHandler>
    </xp:button>

<xp:div id="Div2">
        <xp:table>
            <xp:tr>
                <xp:td>
                    <xp:inputText id="inputText2"></xp:inputText>
                </xp:td>
                <xp:td>
                    <xp:inputText id="inputText3"></xp:inputText>
                </xp:td>
            </xp:tr>
        <xp:tr>
                <xp:td></xp:td>
                <xp:td>
                    <xp:inputText id="inputText4"></xp:inputText>
                </xp:td>
            </xp:tr>
        </xp:table>
    </xp:div>

Ok!!!! Thanks for working this out with me. HUGE HELP!

Don't use rendered = false if you need access to the values because rendered = false does not just hide the contents, they are not rendered at all. I use a computed Style property and set display:none. So I only use the rendered property when I truly  do not want the content hidden and not available. Maybe I'm a slow learner but this took me a lot of hours to figure out. Another work around is to set rendered = false and loaded = true . In this case the values are accessible but not visible. The problem I found with this is that if the control has a default value it does not appear to be computed. I personally like the display:none better because the rule can be contained in a single property, then use rendered when simply do not want the control to be part of the XPage at all.