Domain name showing instead of DisplayName (DN Error)

Question

Hi
For a portion of our users, myself included the Domain\UserName shows in sharepoint but for the majority of users it shows the display name fine.
I've done a full user profile synch today and also restarted the Forefront Identity Manager Service & Synch but it's still nto fixed.
The weird thing is from seeing other people's problems they generally have everyone with domain name but it's a mixture here on my farm.
Here's the error from the Application log;
The extensible extension returned an unsupported error.
The stack trace is:
"System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.InvalidOperationException: More than one DN specified for the same profile.
   at Microsoft.Office.Server.UserProfiles.ProfileImportExportService.UpdateWithProfileChangeData(Int64 importExportId, ProfileChangeData[] profileChangeData)
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle._InvokeMethodFast(Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Microsoft.Office.Server.WebServiceDirectProxy.WebMethodInfo.Invoke(Object webServiceInstance, Object[] args)
   at Microsoft.Office.Server.WebServiceDirectProxy.Invoke(String methodName, Object[] args)
   at Microsoft.Office.Server.UserProfiles.ManagementAgent.ProfileImportExportDirect.UpdateWithProfileChangeData(Int64 importExportId, ProfileChangeData[] profileChangeData)
   at Microsoft.Office.Server.UserProfiles.ManagementAgent.ProfileImportExportExtension.Microsoft.MetadirectoryServices.IMAExtensibleCallExport.ExportEntry(ModificationType modificationType, String[] changedAttributes, CSEntry csentry)
Forefront Identity Manager 4.0.2450.47"

Answer 1

Right now got the service running again, but the following powershell error - can anyone explain please?  Can i just paste a powershell command in and it work??  Firstly go the UP GUID from Get-SPServiceInstance and then tried to run
$upsa = Get-SPServiceApplication –Id 0e2c7f6c-d9f8-43a3-9f56-427f681d5866  $upsa.NetBIOSDomainNamesEnabled=1
$upsa.Update()
But I get....
PS C:\Users\sharepoint> $upsa = Get-SPServiceApplication -Id 0e2c7f6c-d9f
8-43a3-9f56-427f681d5866  $upsa.NetBIOSDomainNamesEnabled=1
Get-SPServiceApplication : A positional parameter cannot be found that accepts
argument '$null'.
At line:1 char:33
+ $upsa = Get-SPServiceApplication <<<<  -Id 0e2c7f6c-d9f8-43a3-9f56-427f681d58
66  $upsa.NetBIOSDomainNamesEnabled=1
    + CategoryInfo          : InvalidArgument: (:) [Get-SPServiceApplication],
    ParameterBindingException
    + FullyQualifiedErrorId : PositionalParameterNotFound,Microsoft.SharePoint
   .PowerShell.SPCmdletGetServiceApplication
PS C:\Users\sharepoint> $upsa.Update()
You cannot call a method on a null-valued expression.
At line:1 char:13
+ $upsa.Update <<<< ()
    + CategoryInfo          : InvalidOperation: (Update:String) [], RuntimeExc
   eption
    + FullyQualifiedErrorId : InvokeMethodOnNull