gtforce

I think, the culprit is my VPN connection. After I tried a number of
things, messing with my network settings, now (I don't know why now,
and it wasn't before) after I log into Windows, the first time I use
the browser, it asks if I need to connect to my VPN. I choose "Do not
ask again" and cancel, and everything works fine.

I don't really know what's the connection between VPN and Base
Filtering Engine service, but there seems to be a bug in Vista about
VPN, since I remember reading somewhere one other guy saying that he
had trouble with his internet connection, and turned out it was his
VPN, so he removed it. At least, I did not need to remove mine.

VPN should engage, when you ask it to connect, and should stay silent,
when it's disconnected. Clearly, for some reason only MS knows, that
is NOT the case in Vista. The VPN connection interferes with your
regular direct connection, even when it's disconnected, and this is
what is causing trouble. I hope MS will fix this in Vista SP1.