Since I upgraded to Snow Leopard (Mac OS X 10.6) I have been unable to download programmes using the BBC iPlayer Desktop.  It worked fine before, but the upgrade killed it.

I tried uninstalling it, removing it using AppCleaner, uninstalling Adobe AIR, restarting etc etc, and eventually just gave up.

Today however I solved the problem!

I uninstalled iPlayer Desktop using AppCleaner, and then deleted the directory:

~/Library/Application Support/Adobe/AIR

Where ~/ is your home directory.

I then went back to the iPlayer website, reinstalled iPlayer Desktop, and now all works fine!

I hope this helps someone else.