Expert Help needed, with XP System functions

A friend has XP Home SP1 using an internal modem to connect to the WWW.
A few days ago he found that Windows Update stopped working. Could get to
the site, click on Scan and it stopped at 0%.
Followed all the likely fixes in the site FAQ without any change in the
situation.
Now the following has also happened:-
1.System Restore starts but will not restore to a past date.
2.He deleted his Dial Up Connection and tried to make a new one, but the
Modem selection is greyed out despite the modem being installed + drivers
and working using HyperTerminal.
3. sfc /scannow will not run.
4. Has tried to Repair XP using the install function in Setup and it
completed but the above 1,2,3 still not working.

The XP auxiliary programmes, Notepad,WordPad,paint and mediaplayer all work
as does all the installed 3rd party software. No new software has been
installed in the past 3 months.
He uses Norton and has had no problems for sometime. All this is new.

Can anyone help us as I am sure all these problems are connected.

--
Paul Woodsford
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