Network Icon Problems

[Guest]

When I boot up my computer the little network icon on the taskbar says
I'm not connected to anything (it has an X over the computers), but I am
connected because I can use the internet. Also, whenever I try to access the
network and sharing center or the 'connect to' windows, they take a very long
time to load. The network and sharing center window isn't even responsive; i
usually have to close it with the task manager.
This didn't happen when my computer came out of the box (pre-installed
with Vista), but started happening after I downloaded some programs for it
(iTunes, OpenOffice, GIMP...) and I don't think I have any viruses that would
cause this problem (checked with AVAST). Are there any solutions to this
problem? Is it a certain program I downloaded? Any help would be appreciated.

 

[Guest]

I'm having the same problem as the both of you. I've determined that it's
also causing my Windows Media Center to not load the extender for my 360 and
it won't download the update for my Zune. Manly because sharing is disabled
somehow on the network and I can't change it. I can't even click the network
window.