Selecting several files with the keyboard: CTRL - mouseclick toggles 1 file and keeps selected. SHIFT-click selects between last selected and now selected, but SHIFT-CTRL-click does not register the SHIFT funktion, so instead of selecting all files between previous click and this one, it only selects this file.

It should work like this:

click #select 1
shift-click #select batch between 1 and this click
Ctrl-click #select another while keeping above selection
shift-ctrl-click #select second batch between last ctrl-click and this
    one while keeping first selection

Other information: