dial up icon vanished?

Windows XP. Dial up connection only. Windows Defender and AVG. Everything
was fine until last MS Tuesday when SP3 came out. Took half a day to get it
with the dialup but I allowed 'auto updates' to do its thing. Seemed to
install okay, but after the reboot my 'network connections' are all messed
up.

I no longer get any indication of progress while dialing out or when the
connection occurs.
No connected icon shows in the task bar (which of course means I can't
readily tell if I am online, nor can I check duration or firewall state).
going to 'connect to' shows the connection icon as Disconnected, even when
it isn't.
going to properties for the icon in the 'network connections' or 'connect
to' windows shows the check mark to display the status in the taskbar is
indeed already checked.
Any attempt to change the checkmark while on line generates the appropriate
'the connection is active..' message, but at the same time the icon says the
system is disconnected.

All actual Internet functionality seems normal, minus the missing icon, and
the incorrect status of the connection being shown in 'connect to'. Of
course because I am no longer shown the status of any new connection, I not
only don't know the baud speed of the connection, nor do I get any indication
of a connection until testing with a browser.

Because the icon shows the status as already disconnected, right clicking to
actually accomplish a disconnect is no longer an option and accomplishing an
actual disconnect requires a physical disconnect of the modem wire. The
system then tries to redial out and 'cancel' is needed to shut the connection
down.

I tried uninstalling the connection and rebooting many times. Each time as
soon as I 'create a new connection' and connect, the icon doesn't appear in
the task bar and the connection stays 'disconnected', although it isn't.

I tried the free help from the MS phone staff and the only advise given is
to try to remove the SP3 in safe mode (did that) and see if that brings
things back to normal. It didn't.

One interesting clue to what is happening occured during one of the help
sessions when a program "Team Viewer" was used by one technician. As soon as
we had the Team Viewer connection made, my dial up icon suddenly reappeared
and everything jumped to normal operation. Suddenly the connection status
properly showed 'connected.' The second we disconnected the problem
returned. Reconnecting to the Internet again showed no taskbar icon even
though the 'display this connection' checkmark was checked, and again the
icon in 'connect to' said disconnected although it wasn't. A reconnect with
the other guy's PC was done with Team Viewer, and again magically the normal
operation was restored and the icon magically appeared in my taskbar. Only
to vanish seconds later when the connection to the other PC was terminated.
Kind of frustrating to have the problem suddenly vanish as soon as the
technician tries to take a look at it.

My suspicion is SP3 made something change deep down inside the Network
Tools. Perhaps a registry toggle? Since connecting to another PC with "Team
Viewer" restores normal operation for the duration of the connection, I don't
believe anything was deleted, per se, just toggled off, then on and off again
during the Team Viewer experience.

Where is the misbehaving toggle and how do I reset it for normal operation?