>When I want to copy a section of an article, say a code section, so I can use it eventually in a method or program, I find that this is possible from the online version of the magazine, but I could not do it from the purchased downloaded copy. Is this something that is true across the board? I hope it's not due to a problem with my machine... ;(

There is no difference between the two copies. Cut and paste should be used as is in both media. Is this something that you can verify with another PC?