Get-Notification, request failed (404 error)

Hi,

The following error has started appearing on our Exchange Server 2013 server's MSExchange Management event logs:

Cmdlet failed. Cmdlet Get-Notification, parameters {Summary=True}.

Since this started happening, I'm also seeing 404 errors on the EAC. Running the "Get-Notification" command manually gives this message:

The request failed. The remote server returned an error: (404) Not Found.
 + CategoryInfo : NotSpecified: (:) [Get-Notification], DataSourceOperationException
 + FullyQualifiedErrorId : [Server=SERVER,RequestId=cd2a0bf4-3311-44cd-91bf-5aa2bbac964e,TimeStamp=3/17/2014 6:29: 51 PM] [FailureCategory=Cmdlet-DataSourceOperationException] 375B5976,Microsoft.Exchange.Management.StoreTasks.Get Notification
 + PSComputerName : server.example.com

How does one debug this? Is this an issue with Exchange's virtual directories in IIS?

Thanks for any help!