Error on Contact form

On contact form there is an error  and error details are here:

Unhandled Exception: System.ServiceModel.FaultException`1[[Microsoft.Xrm.Sdk.OrganizationServiceFault, Microsoft.Xrm.Sdk, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]: System.Xml.XmlException: Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #53F3E72EDetail:

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

 <ErrorCode>-2147220970</ErrorCode>

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

 <Message>System.Xml.XmlException: Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #53F3E72E</Message>

 <Timestamp>2013-08-08T04:46:59.9522623Z</Timestamp>

 <InnerFault>

   <ErrorCode>-2147217104</ErrorCode>

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

   <Message>Table alias a_841bd723774ee211b42900155d0a5b01 is not unique amongst all top-level table and join aliases</Message>

   <Timestamp>2013-08-08T04:46:59.9522623Z</Timestamp>

   <InnerFault i:nil="true" />

   <TraceText i:nil="true" />

 </InnerFault>

 <TraceText i:nil="true" />

</OrganizationServiceFault>

How to fix this?