Many thanks again for the quick response...and your perseverence!!
I had previously seen the FourCC issue on other tech forum and tried AVI FourCC changer to no avail, having been put off by the 'default' settings of MP41, MP42,MP42, DIV4.
However, after you reply I decided to persevere (you did, so I should!!) and the problem was solved by typing "xvid" and "XVID" into the "Description Code" and "Used Codec" respective - voila!! it worked!
I now look forward to many happy hours changing my previous divX videos to Xvid - Mr Google is trying to find me a batch convertor as we speak!!
You are an absolute star, I hope that your excellent answer to my my dumb question has helped others. A beer is in the post.
PR