Ha!
Sorted it. Had the same problem with Mediafire - just got a message about firewalls and cookies - so I tried plan F version 1.07b instead.
In other words I used Firefox instead of Explorer, and it worked a treat first time from Filefront.
Thanks again lads for all your help and tips.
BTW, this is a very active forum - I couldn't believe how far down I had to scroll to get back to this thread!
Am now all set to sink a few pesky battleships
. It may be some time before I'm back on the forum....