Error while trying to login to Desktop Connection for SAP CRM

Hi,

When I am trying to login to Desktop connection for SAP CRM and I getting this error " The underlying connection was closed: An unexpected error occured on a send"

Basically, I have done the configuration by refering to DC_ADMINGUIDE-24-JAN-14.

I am not sure what is the root cause.

Could anyone please advice on this issue?

Thanks and regards,
Shu Jie