Cursor keys no longer jump between cells but move entire sheet

[searcher]

today I noticed “a sudden” change in behavior of the cursor (arrow) keys
in that, e.g. up or down arrow keys no longer jump from cell to cell up
or down, but have instead move the entire sheet as if I used the scroll
bar … (in Calc, that is)

Had just upgraded from 5.4.0 to 5.4.0_Rev_2.

So, I went back to 5.4.0 but the behavior persisted … I might have hit
some mysterious key combination by accident, though …

This is very annoying as I´m using arrow keys frequently to select adjacent
cells; any help more than appreciated

Rgds

[searcher]

addition: I´m using LibreOffice Portable; have now de-installed and removed any trace of it;
then installed 5.4.0.3 completely anew - same behavior; which leads me to suspect this is
some weird MSFT Win 10 behavior, introduced “through the backdoor” … in analogy, every once
in a while, Windows alters my default browser from Firefox into MSFT Edge, so I have to manually
re-set it …

correction: just found the resolution - I just happened to remember that I failed to group columns
by hitting “function”/F12, whereas I should have hit F12 only … tried this a few times and indeed,
it changes the behaviour of cursor keys - it´s now back to normal (big sigh)

[Grumpyom]

Had suddenly developed the loss of cursor key navigation, and reading the comments here have provided the answer - so thank you! My problem was down to my use of a KVM Switch which uses the scroll lock (ScrLk) key to switch between KVM inputs - press ScrLk key twice, then number of input (in my case 1 to 4). If pressed an odd number of times, the ScrLk indicator on my keyboard illuminates and I get the problem described. So no longer an issue for me (LibreOffice 5.3.6.1 just installed).

[Grumpyom]

Had suddenly developed the loss of cursor key navigation, and reading the comments here have provided the answer - so thank you! My problem was down to my use of a KVM Switch which uses the scroll lock (ScrLk) key to switch between KVM inputs - press ScrLk key twice, then number of input (in my case 1 to 4). If pressed an odd number of times, the ScrLk indicator on my keyboard illuminates and I get the problem described. So no longer an issue for me (LibreOffice 5.3.6.1 just installed).