Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support

hi, i m geting this error in crm online..when i assing  any record to  another user...

Unhandled Exception: System.ServiceModel.FaultException`1[[Microsoft.Xrm.Sdk.OrganizationServiceFault, Microsoft.Xrm.Sdk, Version=5.0.0.0,

 Culture=neutral, PublicKeyToken=31bf3856ad364e35]]: System.Web.HttpUnhandledException: 

Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #E004CF27Detail: 

<OrganizationServiceFault xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.microsoft.com/xrm/2011/Contracts">

  <ErrorCode>-2147220970</ErrorCode>

  <ErrorDetails xmlns:d2p1="http://schemas.datacontract.org/2004/07/System.Collections.Generic" />

  <Message>System.Web.HttpUnhandledException: Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #E004CF27</Message>

  <Timestamp>2013-01-22T09:28:06.5212401Z</Timestamp>

  <InnerFault>

    <ErrorCode>-2147220943</ErrorCode>

    <ErrorDetails xmlns:d3p1="http://schemas.datacontract.org/2004/07/System.Collections.Generic" />

    <Message>Principal user (Id=76f926e9-a03a-e211-9214-984be17313a9, type=8) is missing prvReadAccount privilege

                            (Id=886b280c-6396-4d56-a0a3-2c1b0a50ceb0)</Message>

    <Timestamp>2013-01-22T09:28:06.5212401Z</Timestamp>

    <InnerFault i:nil="true" />

    <TraceText i:nil="true" />

  </InnerFault>

  <TraceText i:nil="true" />

</OrganizationServiceFault>

help plz.......