Good morning.

I am having a problem navigating excel, and can't seem to find the
cause.

Both the control and shift keys work fine alone. Control + any of the
arrows is jumping me around. Shift + any of the arrows is moving and
selecting cells.

Control+Shift+Left/Right is allowing me to select blocks of cells as
it normally would. However, my problem is that the combination is NOT
working with the up/down arrows (which also both work, exhibited by
the use of them with ctrl or shift, individually). Any ideas on what
could be causing this?