Picky, Richard, E-Liam,
Thank-you all.
My friend is going away for a week or so, so I won't be able to do much until he returns.
I think first of all I'll try a re-install of XP over the top of the current installation. If that doesn't fix the problem then I'll take up E-Liam's invitation with HijackThis. Much appreciated, E-L.
Happy Easter (or whatever, according to your creed) to all,
AA