Thanks very much for your help esmi.
I tried all the suggestions you made except replacing the folders and nothing seemed to help. I left the site alone for a few days over the long weekend and was about to replace the folders yesterday when I noticed that the problem seems to have fixed itself. Strange.
Not sure if my web host was making changes to the server that could have affected things. He says not but the issue was there and now it’s gone.
Anyway, seems all is OK now.
??
Susan