Calling a web service gives "Unable to connect to remote server error"

I am calling a web service from .net development environment located on my company's server. Everything was working fine until yesterday and it was returning correct data. However, today it suddenly gives me an error "Unable to connect to remote server". I entered the service URL in the browser, and that works fine. Does anybody have any idea what this problem could be about?

First thing that comes to my mind is that the proxy configuration is now different between your application and your browser. Alternatively, it could be an antivirus program running on your machine that had its configuration updated.