Thanks for the replies.
I tried uninstalling the Netcraft Toolbar on IE - this had no effect (Netcraft, incidentally, is a Toolbar that gives an indication of the risk of a website, based on known data. I've never had a problem with it & installed it after a recommendation from a pc security book).
Then I tried disabling my Zonealarm internet security suite (this is the full package, not just a Firewall). Guess what? Now I can download Images!!
Only one problem - I can't run with my Zonealarm disabled, so what can I do?
Thanks.
Polybear.