Some programs cannot connect to the Internet

I've posted this on the Official Windows Newsgroup before, but received no help.

I have a problem which is preventing almost all of my programs from using the
Internet.

I have four different web browsers installed: Microsoft Internet Explorer,
Avant, Opera and Firefox.
At the moment, only IE and FireFox work properly.
Avant and Opera act as if my PC is not connected to the Internet at all.
When I try to access a web page, I get the 'page could not be found' as if a
page did not exist or as if I had no connection. The error page comes up
immediately - the browsers do not even spend time looking for a page or
waiting for a response. The update button on each browser also gives me a
'could not connect' error.

Outlook Express appears to be suffering the same problem - it acts as if I
have no connection active.
Several of my other programs also seem afflicted, but only when trying to
get information from the Internet.

It appears that my programs think that there is no available Internet
connection.

I have already tried adding affected programs to my firewall's exception
list - I have even gone as far as switching the firewall off (I use SP2's built-in Firewall).
I have tried to use System Restore as far back as possible, to no avail.
However, I have had this problem for a long time so perhaps I made a change
before my earliest remaining Restore Point.
And yes, I am certain that I am, in fact, connected to the Internet. I am
using Dial-Up ADSL (my computer has always treated it as ordinary dialup),
and as far as I can remember I have not changed the Properties of my
connection since a long time before this problem begun - my backup
connections also give the same problem, so it seems unrelated to that. I have
not changed my hardware configuration either.

My antivirus program is up-to-date and reports no infections.
My Ad-Aware definitions are 24 days old, and it too is afflicted by my
problem, so the auto-update does not work. The version that I do have
reports only a few tracking cookies, but removing these does not fix my
problem.

Also, I have an interesting update on my situation: Firefox just updated itself,
and now it too no longer works.
It is starting to look like only programs that I have recently updated or
installed are afflicted by this problem.

Short of reinstalling Windows, could somebody please help me to correct this?
Thanks in advance,
-Deek

 

It sounds like a firewall issue. Probably a recent patch / update altered these programs sufficiently to cause your firewall to not allow them access.
Try with the firewalls off, if this solves the problem, then go and rerun the firewall program access wizard.

 

Doesn't appear to be a firewall.

Settings to Look at: Add/Remove > Set Program Access Defaults in left panel.

Regards - Charles