MS WSUS 3.0 Synchronization Failing

Hi experts,
I'm new to WSUS.  I've read up enough about it to know my way around the UI.  Question is:  when I go to manually synchronize, it is constantly failing with this error:

ArgumentNullException: Value cannot be null.
Parameter name: source
at System.Runtime.InteropServices.Marshal.CopyToManaged(IntPtr source, Object destination, Int32 startIndex, Int32 length)
   at Microsoft.UpdateServices.Internal.CabUtilities.CreateMemoryCab(String src)
   at Microsoft.UpdateServices.Internal.DatabaseAccess.CommonDataAccess.ExecuteSPImportUpdateXmlFragments(UpdateFragments updateFragment, Boolean overrideCoreXmlCompression)
   at Microsoft.UpdateServices.Internal.DatabaseAccess.CommonDataAccess.ImportUpdate(Int32 ussRevLocalId, String xmlUpdateBlob, Byte[] xmlUpdateBlobCompressed, String xmlSdpBlob, Int32& localRevisionId)
   at Microsoft.UpdateServices.Internal.DatabaseAccess.CommonDataAccess.ImportUpdateWithFileUrls(Int32 upstreamServerLocalId, String xmlUpdateBlob, Byte[] xmlUpdateBlobCompressed, String xmlSdpBlob, ServerSyncUrlData[] fileUrls, Boolean setCatalogSiteFlag, Guid updateId)
   at Microsoft.UpdateServices.ServerSync.CatalogSyncAgentCore.ImportSingleUpdate(ServerSyncUpdateData updateData, List`1 allFileUrls)
   at...

We have our upstream server pointed to a .MIL WSUS server and not pointed directly at Windows Update.  Can someone please guide me into the right direction to hopefully get this solved.  Black Tuesday is next week and I'd like to have the WSUS server working perfectly by then.  My understanding is that if I can't synchronize the server, the server will not pull down the latest updates, correct?

Please advise.  I'm grateful for any suggestions or comments.  Help welcomed!

Y