Heh - the SingStar team on the Facebook page told me how to fix it. Apparently I had to change the wallpaper in the game, which would allow me to reboot and download the patch - and it worked. Who'd've thought the wallpaper was the problem...

I'm glad it was something as counter-intuitive as that, rather than me just being thick. Thanks for your advice anyway - I'll be changing the autoplay option now I know how to.

Ooh, you haven't given me five things from that meme yet btw. Just don't make 'techofear' one of them ;-).