[PC] 'Options' problem: can't scroll up or down with mouse or keyboard

I have experienced the same problem. Not a frequent thing. Just a few times.

I think I just clicked somewhere else as middlefngrsalute suggests. Or maybe I used the escape button or something like that. The point is to get out of what's freezing/stalling.

It means you can't save when this happens?

I don't know how many 'layers' there are in the user interface? There must be several functions working at the same time. I heard this in connection with another game. There are many small utilities/programs running at the same time.