Experiencing an issue when attempting to delete a queue - error message received

I am working in Microsoft Dynamics CRM 2011 on prem.

I am having issues simply deleting a queue. It says there is something in the queue however when I browse to the queue, there are no queue items present.

I've tried multiple views "view everything that entered the queue" etc and still no queue items show.

Any ideas?

Log -

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: #20DB7AD0Detail:
<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.Web.HttpUnhandledException: Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #20DB7AD0</Message>
  <Timestamp>2015-07-10T18:29:18.4677642Z</Timestamp>
  <InnerFault>
    <ErrorCode>-2140991209</ErrorCode>
    <ErrorDetails xmlns:d3p1="schemas.datacontract.org/.../System.Collections.Generic" />
    <Message>Cannot delete queue which contains queue items</Message>
    <Timestamp>2015-07-10T18:29:18.4677642Z</Timestamp>
    <InnerFault i:nil="true" />
    <TraceText i:nil="true" />
  </InnerFault>
  <TraceText i:nil="true" />
</OrganizationServiceFault>