Internet connection is screwing around :(

It started about 4 months ago:

I surfed in the net, and then my friends called me out,...when i came back the computer didn't connect to the net anymore. But the IP was showing in winipcfg(or something)...

This lasted for some time(i had to surf in Linux)...and then i tryed all sorts of things...one of them was removing the Proxy aadress from connections. Then it started working again...

but then again...some time ago, the connection lost. The ip is showing....but no connection.

I have tryed with the proxy without the proxy and so on...and the proxy is correct(checked it today with my ISP)

Please help...i guess only those who have handeled a situation like this before know what to do.

Please...don't want to format

 

PLz answer