I'm surprised at how bitter those responses are. Of course I will help friends and family with their computer problems -- they are my friends and my family! When I run into trouble and need their help I would hope they'd be there for me...
Generally, doing it for friends and family shouldn't be a problem. Occasionally though people expect miracles, they expect them fast, and they're pretty ungrateful.
It's also easy to be sucked in by acquaintances like this: "Can you have a look at my PC after work? It won't take very long and I'll make you dinner." to which you of course agree. The bad part comes later, because you've just set a precedent and evenings like this will keep repeating. Those people think two afterwork hours of fiddling with their ancient Windows crap is worth exactly one burrito and a Sprite. Yeah, it happened to me recently.