XBox 360 and 80070003

I wonder what this error really means.

XBox Live is currently sorta-down, and it's been in a sorta-down state for the last two days.  Games mostly work, the forums on are down, and XBox Live has just been flaky.  Sometimes I can't connect, but when I can, trying to download the new Lumines game gives me this error.

Googling for this error finds sites that say it has to do with there not being enough disk space available, but I have plenty of space.

So apparently 80070003 seems to be some sort of "general failure".  Oh well, at least I'm not alone.

(XBox Live has been an incredibly reliable service for me - it usually just works).