Pfffff, I think I just figured out what my problem was: for some stupid reason, Windows doesn't always copy the currently selected text in whatever editor is open if I just press Ctrl-C
once - I have to do it multiple times. This has been the case, in my experience, for many years, so I've developed the habit of always pressing Ctrl-C 2-3 times whenever I want to copy the current selection (whatever selection, whatever program it's in; and no, it's not my keyboard - I've used many keyboards over the years and I've never had any special problems typing the letter "C"). The problem in SlickEdit is that after the first (successful) Ctrl-C is registered, the selection disappears and all I'm left with is the text cursor being on the current line. In these conditions, my next Ctrl-C will copy the
entire line and overwrite what I previously had in the clipboard and by the time I move over to my destination to do the Ctrl-V, I'll be in for that irritating surprise I was talking about.

All because I had the "Deselect after copy" option checked. *bashes head against wall*