for certain definitions of intelligentYes, but I would argue that those definitions are not really relevant to this discussion. You say...
behavior does not have to be self-directed to be intelligent
...which is true, but the whole point of AI is to get to a point where computers are self-directed; where we don't have to laboriously tell the computer what to do; we just give it a general goal statement and it figures out how to accomplish it. If we have to continuously intervene to get it to do what we want, what's the point? We have that now. So this...
Its (supposed) neural network could be modified externally without any self-direction whatsoever.
...is also not really relevant, because the whole point is to develop AI's that can modify their own neural networks (or whatever internal structures they end up having) as an ongoing process, the way humans do.
(Btw, one of the reasons I keep saying this is "the whole point" is that developing such AI's would confer a huge competitive advantage, compared to the "intelligent" machines we have now, that only exhibit "intelligent" behavior with continuous human intervention. So it's not realistic to limit discussion to the latter kind of machines; even if you personally don't want to take the next step, somebody else will.)
The word "being" perhaps is the stumbling point here.
No, I think it's the word "intelligent". See above.
I don't think there is any programming error that could turn an intended knowledge-loving machine into a self-preserving amoral humanity killer.
I don't think you're trying hard enough to imagine what effects a programming error could have. Have you read any of Eliezer Yudkowsky's articles on the Friendly AI problem?
The architecture of the two would be vastly different.
Why would this have to be the case? Human beings implement both behaviors quite handily on the same architecture.