Pretty (annoying) blue cables

Ive seen plenty of weird network problems. But this one is just to stupid:

Sometimes my network connection stops working, it shows up as "media disconnected" in windows. Try all sorts of things, eventually give up and reboot, problem still there. Eventually grab another blue cable out of the pile and plug one end into the computer and the other into the wall, and "voila!" everything is working.

So now I just think, OK, dodgy cable, no problem, move along. But wait...
a week or so later, same problem again! Now this time I went and got a brand new, still in the wrapper cable from the cupboard (you know, one that came with some piece of previously purchased hardware), plug it in, and away we go again. Nice, two dodgy cables, bit of bad luck there.

So fast forward another week, and after pulling nonfunctional computer apart (yes, my graphics card toasted itself, lucky there was an old one in aforementioned cupboard), network problem again! WTF!

This time I don't bother getting another cable, just grab one of the previous two, both still hiding conveniently under the desk, and plug it it... it works.

Why do my network cables just stop and start working like this? It does not make much sense...

I need a new "WTF" tag.