By chance, are you using custom input settings for another language? If so,
the sequences you mention may not be set to open a search window. But you
can customize your settings so that you may have them.
Type "shortcut keys" in the "Help and Support" query field, and see the
selection of options on your left. There is a link to how to customize your
shortcut keys.
By the way... windows-key+F, opens Windows Explorer Search, but ctrl+F just
opens a text search box... They are two different functions altogether.
Did you know that? This is one reason I suspect you are using an alternate
key-map.
