GUYS!!
Suddenly, without any apparent reason (to me, at least at this stage), I am connected to the internet on all computers...
All I can say is that something changed on the problematic computer without running WinsockxpFix and without running any anti-spyware programs. The virus scans have fouond no viruses on the problematic computer although when I ran Adware on one of the working computers it found a number of things it didn't like. these it deleted.
I assume that this could have been the reason? I mean, is it possible for a virus.adware/spyware or whatever to get on one computer and block another of the computers (not both the other two computers) from getting on the internet?
I am confused.
Admittedly, all computers have been turned off and on several times during the last couple of days and I don't know if the combination of turning one or the other on at a time when one or more of the other computers was on or off made a difference, but something has worked.
It could even be that the ISP (whom I contacted by email to start with and asked to help me (he never got back to me, by the way!) has made some changes his end. I have no idea.
I would like to that you all for your help and attention and would like to help if there is anything I can do to further clarify what happened in the event that it may be of use to someone else in the future who may get into a similar position as me.
Regards
Joe