Hi All,
One of my user is getting below exception when clicking on lookup field. This is happening for all entites and all forms. This is happening only for particular user.

Unhandled Exception: System.ServiceModel.FaultException`1[[Microsoft.Xrm.Sdk.OrganizationServiceFault, Microsoft.Xrm.Sdk, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]: System.NullReferenceException:
Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #63178CD8Detail:
<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.NullReferenceException: Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #63178CD8</Message>
<Timestamp>2014-10-13T13:21:42.8204934Z</Timestamp>
<InnerFault i:nil="true" />
<TraceText i:nil="true" />
</OrganizationServiceFault>