a connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed....

Hi,
Yesterday we had a problem calling 3rd party webserivce where we received the following error:
a connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond (my external IP address):(port)

I created a web proxy for Secured SSL in c#, but still was not able to establish the connection.

Earlier I created a sample console application which calls the webservice with the same code used in the original application. That console application was able to call the 3rd party webservice and got the result too! We almost wasted a day reasearching for this, though we knew there is some problem with the application configuration. No clue which configuration it was?
Actually, our application executes as tasks (like jobs in sql server) every 15 mins. There was the problem. We had to configure the tasks which permitted the application to call the 3rd party webservice. It worked then!!!