"Cable modem is working perfect, once we plug network into modem, can't get on internet."
You will need to explain a few things, using industry-standard terms. First, I suspect that this not a wiring problem at all, since wires do not stay up late at night to conspire to drive us crazy. Unless a human has gotten his fingers into the situation, wires that worked in the past will work in the present. You are correct when you say "Don't think this could crash network all of a sudden."
That said, please explain what you mean by "cable modem is working perfect." How did you test it? What did you plug into it to determine that it is working "perfect."
Next, what do you mean by "we plug network into modem"? A network, which generally consists of many wires going to many locations, needs a router/switch to create the ports necessary. How did you plug a network into a modem? Have you by-passed the router (assuming there is one) and patched directly from the modem output jack to a single computer's input jack?
Finally, as the other guys have stated, you can use whatever color code you like, as long as the same code is used at both ends of a particular cable.
