Queues will not show when clicking on menu CRM 2013

In Service module I click on Queues, and I get is the error message below. But some normal users can see the normal queues page, when clicking on the Queues (both in IE and Outlook)! I'm logged in as system admin.

Unhandled Exception: System.ServiceModel.FaultException`1[[Microsoft.Xrm.Sdk.OrganizationServiceFault, Microsoft.Xrm.Sdk, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]: System.Xml.XmlException: Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #06987C77Detail:

<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: #06987C77</Message>

 <Timestamp>2013-11-27T15:56:28.3451862Z</Timestamp>

 <InnerFault>

   <ErrorCode>-2147220989</ErrorCode>

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

   <Message>Condition for attribute 'email.activityid': expected argument(s) of type 'System.Guid' but received 'System.Guid[]'.</Message>

   <Timestamp>2013-11-27T15:56:28.3451862Z</Timestamp>

   <InnerFault i:nil="true" />

   <TraceText i:nil="true" />

 </InnerFault>

 <TraceText i:nil="true" />

</OrganizationServiceFault>

Would anyone give me an advice please? thank you very much