says "not connected", sometimes hangs up while connecting.

My new notebook PC I had just bought last month was working very well, and I could use its built in Wireless Connection to connect to my home network. This weekend, however, it stopped working. When I connect to it, sometimes it just keeps saying "waiting for network" or something like that, and refuses to go past that. Most of the time it says I connected in the pop-up with the loading bar, but then in the view wireless connections, it says I'm "not connected"! When I double click it to connect it, it says "Do you want to disconnect"! The little icon on the start menu says I'm not connected, and the internet only works sometimes. Did I do something wrong? I recently installed some stuff. Would it have an effect on my wireless connection?