My wife told me she was told there are were viruses on the desktop , I didn't see how she was told this , and assumed Sophos Antivirus detected them. WRONG !!!
I believe it was the auto update by MS Update that tried to install MS Antivirus automatically . Which would be fine if this was provided free like other updates for XP , but it isn't .
I did a deep scan of the HDD with Sophos (took the trouble of getting their latest update) , not a single infection found.
I later , just now as a matter of fact, discovered this was the likely problem as ,my note book automatically tried to install MS Antivirus and I made the mistake of hitting the run button.
When it detected some infections (yeh sure ,I did a deep Sophos Antivirus scan on Friday and it gave a clean bill of health ,so I know that's BS) anyway hit delete them button it promptly asked me to register the application.... AND NOW THE RUB .... IT requested about $50 to do this... no way Joseh !!!
So I did the uninstall + warm boot , thing ... nope go good

... still interferring and stopping me from visiting sites I know are OK.
SO ... brought out the big guns , SYSTEM RESTORE to a point a few days ago .... seems to have got rid of this BS program.
Hopefully for ever.
Hopefully that's all I need to do never to be bothered by this insideous and nasty bit of software (MS's latest nasty).