Did that to me the other night too. It was just corrupt mobile data on a iffy connection I concluded; as soon as I reloaded the page it worked fine again, and has been OK since. Though curiously like you I'd just reflashed the N900 to the current release, and only hours before.

Why can't the BBC stream like other Internet Radio - using flash for audio is such a pain! The only compensation is the knowledge that all those Apple fanboys at the BBC can't use it on their phones!