Help Unclosable window (possibly a popup)

[Rabelais]

I am sorry if this question has been asked before or is a simple or know issue, but I for the life of me can find no similar type issue with the search terms I have used anywhere on the net.
I have a Galaxy Note 10.1 P600 (2014) running 5.1.1 and it has started throwing up a blank white window with a black cross in the corner that is unclosable.
No program needs to be open and there is nothing on or in the window other than the cross in the corner is not active and back button or multiwindow do not affect it.
You can pull down the system menu bar but any access opens the new window behind the blank window which cannot be seen or accessed.
I have avast running and malwarebyes and they have reported nothing now or leading up to the issue. The Tablet is running non rooted but is on the latest Samsung version of lollipop for the tablet.
Re-flashing this is going to be annoying as the 5.1.1 update means system restore and safe mode are no longer available on startup with power and volume up. It just takes me to an Odin download menu'
Do I have any other options other than a factory reset or siccing Odin on it and re-flashing the ROM and/or has anybody heard of similar?
Apologies again if this is known
Cheers
Paul

 

[Bg260]

I've never heard of the black cross page. From my point of view you have three options.

1. Live with it.
2. Flash stock firmware with Odin.
3. Root it, install recovery, and install a custom ROM

Without knowing your full model, the links are only a guess. Follow up if you want more info.