I think the problem started when Adobe Flash Player updated to version 11. Up till then, the iPlayer app and the Arnova seemed to work fine. Somewhere along the line, the three-way compatibility between the machine and the two apps has been compromised. You could try getting an older version of Flash Player, e.g. 10.1, and installing the .apk file manually but you'll always face the problem of having it update behind your back, setting you back to square one. I've just tried this with 10.1 and it seems to work, but the iPlayer app nags you to update it.

This isn't the first example of the Arnovas needing older apps to function properly - for example, you need to get an older Skype app to make video calling work.