since this morning vvolumio shows only a black screen

I use volumio 2.526 on rasberry
since this morning my browser shows only a black empty screen on my phone as on my laptop.
a new install lets my configure volumio but after volumio has changed the ip address connect is possible
but the screen is always empty.
Any hint?
Thank you

a closer look showed that my Pi was stuck reading sd-card (yellow led constantly on).
An other sd-card solved the problem.