unwanted appearence of input screen mask

[ThomasA]

Hello,
I observe some strange behavior of my prime (hardware model C)
Working in CAS and pressing the Apps/Info button leads to the input screen one usually sees when saving an app

Select new app name
Name: .......
Base App: ........
enter new app name).

The input fields (here symbolically written with dots) are not editable,
in my case they are constantly showing "Linear solver", the name of the app I used before the problem occured which is annoying.
In the past I could always switch between the apps only pressing the Apps-key and then choosing the appropriate icon.
Of course I can't exactly reproduce the steps leading to this status of the machine. I remember, that I sorted the apps for the first time just before the strange things began. Sorry for this vague description!
What can I do to get rid of the unwanted input screen?
Maybe the following observation helps to clear clear the problem:
When the input screen is active I can press the help button. The displayed help text refers to the function app (and not to the actual screen content).

Software version:2018 02 12 (13441)

Thanks in advance
Thomas