Greetings,
I'm using WinXP Pro SP3, automatic updates enabled. Since a couple of days,
IE7 is no longer able to connect to anything, including Windows Update or
even our intranet - which excludes a DNS problem, because I enter directly
the IP address of the machine one floor below. I use Windows built-in
firewall, but even turning it off does not help. My internet connexion (via
University LAN) works well, I can use other browsers without any problem,
email, FTP... everything. Only IE refuses to work, and this means all the
updates passing through IE are stopped.
At first I thougth the culprit could be spybot, but turning off spybot addon
did not solve either. I use F-Secure antivirus, but it had never interfered
with IE. I have Windows Defender on
The connexion panel under Tools > Internet Options > Connexions > LAN
parameters has all the checkboxes cleared. Checking the "automatic
configuration" does not help. I also tried the "reinitalise" buttons under
the "Advanced" tab, no result! The proxy box is clear.
I have only one LAN card, no wireless.
I did a search on the net for similar problems, but all I found was related
either to a firewall or to the proxy box in the "connexion" tab being
checked. I'm clueless, can somebody help?
Thanks so much in advance.

Self-answer - this may be useful for others having the same problem.

I rebooted in safe mode with network and IE worked. That means that somebody
was blocking IE. I had a look at my installation and I found a firewall
(Online Armor) which I had installed when I setup Windows but soon turned off
because too invasive. I unsintalled it and rebooted normally. Now IE works
fine. I have no idea why a firewall that in principle was turned off (Crap
Cleaner confirmed it was off) still did such a damage, but that was the case.