I did see others coming across this behaviour some weeks back.
As u may have read elsewhere, iPlayer in the last release leaks memory like a seive. It seems that after using iplayer, then placing box in standby seems to leak a bit of memory too and so when u come back in the morning there is so little memory left u get the forever waiting arrow when next u try and do something.That can be running an app again or even a next page on the home screen.
I always did a hard power off (long press) as it saves energy and these days allows u to see as much memory as possible when next running apps or video playing. It even cures weird side effects from trying to play a file with strange encoding that mucks up playing other valid videos - leaking codec faults between runs. Rare but I have seen it over the years.
