I am using the multiList query to retrieve a distinct set of status values across four lists each stored on different sites.  I have some users who have access to all of the sites and they are able to run the query with no issues.  When I try to run the query with a restricted user account (user can only access one of the four sites) I receive a 401 access denied error.  I verified that the 'SPLogin' section of the rsreportserver.config file exists with the Login and Password properties. We are currently using version 3.1.427 and I know this worked in the past believe it was v 3.0.  Below is the query I am executing. 

Query:

<?xml version="1.0" encoding="utf-8" ?>
<root xmlns="http://enesyssoftware.com/schemas">
    <multiList title="Protocol" relativeSiteUrl="/sites/PROMIS" type="RollUpList" tableName="Protocol">
    <fields> Protocol_x0020_Status1</fields>
    <query></query>
  </multiList>
    <sqlQuery tableName="MergedProtocols">
        SELECT DISTINCT Protocol_x0020_Status1 from Protocol
     </sqlQuery>
    <resultSet>MergedProtocols</resultSet>
</root>

Report Server Error Message:

w3wp!library!1!07/20/2009-15:22:21:: e ERROR: Throwing Microsoft.ReportingServices.Diagnostics.Utilities.AccessDeniedException: The permissions granted to user 'PROMIS\IRBAdmin' are insufficient for performing this operation., ;
 Info: Microsoft.ReportingServices.Diagnostics.Utilities.AccessDeniedException: The permissions granted to user 'PROMIS\IRBAdmin' are insufficient for performing this operation.

 Update:

We resolved the issue by publishing the datasource and changing the current queries from list queries referencing explicit sites to a multiList query.