Tried to sign out and back in, no luck. Tried again, rebooting the box between signing in and out, no luck.
Netflix opens fine, allows me to watch previews all the way through, but within a minute or less of a movie/episode starting I get a screen that says "We're having trouble playing this title right now. Please try again later or select a different title". My account is current.
This may be relevant - the box is still connected via the AV port to RCA in on the TV. I cannot get the box to work with the original HDMI cable.
Showmax, YouTube etc work fine.