I don't have any real clues at the moment, but I have a question. You said, "I regularly type copy to be used two-up on a page". What does that mean? It may not be relevant to your problem, but you never know.
Does this failure occur only in Word, or does it happen with other text typing, eg when typing a post in these forums. I know it works when typing here as I have just tried it. CTRL + A to highlight all my text, CTRL + C to copy, then open Notepad and CTRL + V to paste into Notepad. It's a good test to see if this is just a problem with Word or generally.
Another question, what has changed since you were last able to do this?
For some reason, I can no longer use Control A, C V to copy . I regularly type copy to be used two-up on a page. Never had a problem until now. Finally tried right clicking on copy and it worked. By why would the normal way be disabled?