Thanks everyone, but it gets Curious & curiouser!
I did a few tests (all with Windows 7)
Word ==> printer OK
Word ==> PDF ==> printer OK
Firefox ==> AOL email ==> printer NOT OK (500+ pages)
Firefox ==> AOL email ==> PDF NOT OK (500+ pages)
Chrome ==> AOL email ==> printer OK
Chrome ==> AOL email ==> PDF OK
So the shadow of doubt seems to hover over Firefox and not AOL as I suspected.