Thank you.
No it is Windows on a portrait screen. I could change the orientation and physically arrange the monitor but I use it for all help files and tutorials etc to give max length to pages and everything else works a treat.
I will wait and see whether you change anything in due course.
[EDIT] I have just noticed that it seems to be mostly the tutorials etc and not so much the posts, so maybe it is something to do with the input source and cr/lf type issue???