Ausatco - I think you might just have hit the nail on the head. Both of us had 4 WEP key selections. I did not realise they had to synchro. My No 1 key I left with my own WEP key and I inserted Son's key in the No 2 slot. I guess that mught be the cause of the problem. When we next get together, I will check it out.
Richard - thanks for the link - very informative, simple, and for my one remaining soggy braincell, a godsend with its pretty pictures!