This has been happening regularly and seems to be associated with a faulty download, which seems strange as it seems to happen when a downloaded track makes its way from my CurrentWeekly to my NMTop100 playlist and both always remain downloaded.
The track gets "stuck" in playback and causes everything to freeze.
That I cannot refresh a download on a single track is your biggest **bleep**. Just let me force re-download a single track and remove the old cached version and the issue will go away.
Allowing me to recognise the filename within the cache by not encrypting it in a ridiculous way would help too.
I don't want to refresh my entire cache when I'm not in a suitable place to do so, i.e. not at home.