Error 104 (net::ERR_CONNECTION_FAILED): The attempt to connect to
 

I am getting this error in my browser on regular basis almost ever hour

Error 104 (net::ERR_CONNECTION_FAILED): The attempt to connect to the server
failed.

after which I am unable to access internet from any of the web browsers in
my PC (IE, Firefox and Chrome). Its surprising that i am still logged on on
msn and skype and keep chatting, yahoo messenger does not work, Outlook
continues to work and I can send and receive message.

I have tried all types of maintenance activities but to no avail. The only
way to resume web browsing is to restart the machine.

Can anyone help me?