Every time I try downloading the latest version, Norton AntiVirus detects something wrong and deletes it. Yet the old version has been running quite happily for many months.

You have two options.

1. Believe Norton - which also found a problem with 3.13 from another thread

or

2. Believe Dinky and the many thousands of other people who have run 3.17 without any virus problems.



If 2. then your course of action is obvious.

i. Turn off Norton whilst you install 3.17
AND
ii. Complain to Norton about their false-positive.

Thanks very much. I have taken your advice, and it now works.