Thank you Brink and Bare Foot Kid
I tried the sfc /scan in an elevated comand prompt, it returned no errors, all files were fine.
Unfortunately this has made no difference.
I tried the FixSingleSelect.vbs script (had to recreate it, the link you posted took you to an under construction site - attached if anyone needs it!)
Again, unfortunately this did not work
I also reset all folder optios to default and again no joy
So ............. no multiple file selection for me
Can anyone help and make any other suggestions please