Event 1003, MSExchange Front End HTTP Proxy

I keep getting the following error: I only have one exchange server 2013, but did migrate over from exchange 2007 which is now decommissioned and not in my domain at all.

Log Name:      Application
Source:        MSExchange Front End HTTP Proxy
Date:          11/22/2013 10:00:18 AM
Event ID:      1003
Task Category: Core
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      com
Description:
[Oab] An internal server error occurred. The unhandled exception was: System.ArgumentNullException: Value cannot be null.
Parameter name: sourceObject
   at Microsoft.Exchange.HttpProxy.AnchorMailbox..ctor(AnchorSource anchorSource, Object sourceObject, IRequestContext requestContext)
   at Microsoft.Exchange.HttpProxy.UserADRawEntryAnchorMailbox..ctor(ADRawEntry adRawEntry, IRequestContext requestContext)
   at Microsoft.Exchange.HttpProxy.OabProxyRequestHandler.ResolveAnchorMailbox()
   at Microsoft.Exchange.HttpProxy.ProxyRequestHandler.InternalBeginCalculateTargetBackEnd(AnchorMailbox& anchorMailbox)
   at Microsoft.Exchange.HttpProxy.ProxyRequestHandler.<BeginCalculateTargetBackEnd>b__27()
   at Microsoft.Exchange.Common.IL.ILUtil.DoTryFilterCatch(TryDelegate tryDelegate, FilterDelegate filterDelegate, CatchDelegate catchDelegate)
Event Xml:

  <System>
    <Provider Name="MSExchange Front End HTTP Proxy" />
    <EventID Qualifiers="49152">1003</EventID>
    <Level>2</Level>
    <Task>1</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2013-11-22T15:00:18.000000000Z" />
    <EventRecordID>1002387</EventRecordID>
    <Channel>Application</Channel>
    <Computer>bmp-exch1.metrohmusa.com</Computer>
    <Security />
  </System>
  <EventData>
    <Data>Oab</Data>
    <Data>System.ArgumentNullException: Value cannot be null.
Parameter name: sourceObject
   at Microsoft.Exchange.HttpProxy.AnchorMailbox..ctor(AnchorSource anchorSource, Object sourceObject, IRequestContext requestContext)
   at Microsoft.Exchange.HttpProxy.UserADRawEntryAnchorMailbox..ctor(ADRawEntry adRawEntry, IRequestContext requestContext)
   at Microsoft.Exchange.HttpProxy.OabProxyRequestHandler.ResolveAnchorMailbox()
   at Microsoft.Exchange.HttpProxy.ProxyRequestHandler.InternalBeginCalculateTargetBackEnd(AnchorMailbox&amp; anchorMailbox)
   at Microsoft.Exchange.HttpProxy.ProxyRequestHandler.&lt;BeginCalculateTargetBackEnd&gt;b__27()
   at Microsoft.Exchange.Common.IL.ILUtil.DoTryFilterCatch(TryDelegate tryDelegate, FilterDelegate filterDelegate, CatchDelegate catchDelegate)</Data>
  </EventData>
</Event>