Issue in password reset using desktop Add Ins utility

Hi,

I am facing  issue when users go for password reset using the SSPR client, they receive error pop-up saying “Could not connect to Password Reset Service”.
We have tried restarted the FIM client machine,repair the FIM add ins on client system,restarted the FIM service,reset IIS etc.
Please suggest to resolve the issue. We have  FIM 2010 R2 SP-1 with latest hotfix.

Error in event log is as below.

Source:        Microsoft.ResourceManagement.PasswordProxy
Event ID:      3
Task Category: None
Level:         Error
Keywords:      Classic
User:          N/A
Description:
PwdMgmtProxy: System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.IdentityManagement.PasswordReset.GinaOperation.STSInitiateCommunication()
   at Microsoft.IdentityManagement.PasswordReset.GinaOperation.STSSubmit(Byte[] gateData)
   at Microsoft.IdentityManagement.PasswordReset.PasswordResetOperation.ValidateUser(ClientPipeContext& client)
   at Microsoft.IdentityManagement.PasswordReset.PasswordResetOperation.Authenticate(ClientPipeContext& client)
   at Microsoft.IdentityManagement.PasswordReset.PasswordManagementProxy.PipeCommunicationThread(Object context)
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Microsoft.ResourceManagement.PasswordProxy" />
    <EventID Qualifiers="0">3</EventID>
    <Level>2</Level>
    <Task>0</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2015-01-14T12:01:46.000000000Z" />
    <EventRecordID>94</EventRecordID>
    <Channel>Forefront Identity Manager</Channel>
    <Security />
  </System>
  <EventData>

Thanks
Harry