Thanks for the quick response!  My "known problems" comment was based on some quick web research that I did on actionpollers and datatables.  I even noticed a comment in the documentation that did not endorse using actionpollers with enhanced lists.

As for my specific issue, I am displaying a list of customers that changes on a constant basis (so that is why I need the actionpoller).  This list uses a commandLink to populate items in a separate pageBlock called "CustDetailInput". This is simply a related list for whatever customer record is clicked.

I am able to enter these customer interaction records without problems most of the time.  However, let's say I do the following....1) click on a customer name; 2) enter two interaction records;  3) then press the "Submit Interactions" button;  4) then click on the same customer name in the customer list...and repeat this sequence four times.

The problem with the above is that I am seeing errors on the fifth or sizth above cycle.  My investigation has shown me that the ID of the Customer__c record is not properly passed on this fifth or sixth cycle - instead it is blank.  I am confident that the actionPoller is causing this because all is fine when I remove the actionpoller line of code (and I am able to do many cycles of the above).

Any thoughts would be greatly appreciated...also, to answer a question of yours, my understanding is that the the poller is outside of the table.

Thanks much.

<apex:pageBlock title="Customer Overview"> 
<apex:dataTable value="{!Customers}" var="Cust" id="CustList" width="100%" > 
 <apex:column > 
  <apex:facet name="header"><b>Customer Name</b></apex:facet> 
  <apex:commandLink action="{!invokeService}"
                    value="{!Cust.CustName__c}" rerender="blockA, blockB">
    <apex:param name="xxx" value="{!Cust.id}"/>
  </apex:commandLink>
 </apex:column> 
</apex:dataTable> 
<apex:actionPoller rerender="CustList" interval="5"/>
</apex:pageBlock>

<apex:commandButton action="{!Detailsinput}" value="Enter Interaction" rerender="CustDetailInput, OtherBlock"/>


<apex:outputPanel id="CustDetailInput">
<apex:pageBlock title="Customer Details" rendered="{!NOT(ISNULL(showCustDetailInput))}">
<apex:pageBlockButtons location="top">
<apex:commandButton value="Submit Interactions" action="{!saveCustDetails}" rerender="OtherBlock, CustDetailInput, blockB, CustList"/>
</apex:pageBlockButtons>
<apex:dataTable columns="2" value="{!detailEntry}" var="a" width="100%">
<apex:column > 
<b>Interaction</b>
<apex:inputField value="{!a.Interaction__c}"/> 
</apex:column>
<apex:column > 
<b>Notes</b>
<apex:inputField value="{!a.Notes__c}"/> 
</apex:column>
<apex:facet name="header">            
<apex:commandButton value="Add Interaction Item" action="{!addIntItem}"/>