SharePoint / AD Sync error :: stopped-extension-dll-exception

Hi All,

I have been looking at a system with an AD -> SharePoint sync failure. The Full sync runs but no AD updates are sent to SharePoint, Profile mappings and OU connections are all okay. The FIM client is showing the stopped-extension-dll-exception error and in the event log the stack trace is below, does anyone know what the path format error in the stack trace refers to  before I recreate the UPS ?

The extensible extension returned an unsupported error.

The stack trace is:

 "System.NotSupportedException: The given path's format is not supported.

   at System.Security.Util.StringExpressionSet.CanonicalizePath(String path, Boolean needFullPath)

   at System.Security.Util.StringExpressionSet.CreateListFromExpressions(String[] str, Boolean needFullPath)

   at System.Security.Permissions.FileIOPermission.AddPathList(FileIOPermissionAccess access, AccessControlActions control, String[] pathListOrig, Boolean checkForDuplicates, Boolean needFullPath, Boolean copyPathList)

   at System.Security.Permissions.FileIOPermission..ctor(FileIOPermissionAccess access, String path)

   at System.Web.Hosting.SimpleWorkerRequest.GetAppPathTranslated()

   at System.Web.HttpRequest.FillInServerVariablesCollection()

   at System.Web.HttpServerVarsCollection.Populate()

   at System.Web.HttpServerVarsCollection.Get(String name)

   at Microsoft.Office.Server.WebServiceDirectProxy.InitHttpContext(Uri uri)

   at Microsoft.Office.Server.UserProfiles.ManagementAgent.ProfileImportExportExtension.InitializeImportExportWebService(String serviceUrl, NetworkCredential credential)

   at Microsoft.Office.Server.UserProfiles.ManagementAgent.ProfileImportExportExtension.Microsoft.MetadirectoryServices.IMAExtensibleCallExport.BeginExport(String connectTo, String user, String password, ConfigParameterCollection configParameters, TypeDescriptionCollection types)

Forefront Identity Manager 4.0.2450.34"