I'm so sorry, but I should have explained more in my original post .....
That arrow doesn't show up in my top bar during the download and when I go to my Downloads folder, there is nothing there but some really old files downloaded a long time ago. It's like a setting got changed or switched off somehow.
When I try to open a pdf file, the little notification pops up down at the bottom of my screen ("download started") and then disappears almost immediately, but nothing else happens anywhere else on the screen and there is nothing in my "Downloads" folder.
It's all very odd because I did not have this problem before and it's like something got changed.
Sent from my GN2