I don't think it's anything wrong with the OS...
Me neither, but I was thinking of a however low but still probability that a certain Windows version/build could not be "friends" with certain... I don't know.
As you're saying other browsers are o'k, and offline documents are o'k too - aren't they? So I think what?
You said Chrome too, right?
So if it's (only) nuOpera and Chrome - then as long as they share things, it might be an extention/plugin you or somebody else had got for Google Chrome and that it happened that it (unknowingly for you then) proved itself incompatible with Chrome in a certain way.
If you even uninstalled Chrome, certain apps might've survived and remained on your machine active, and now they might've applied themselves to your nuOpera - and the same way corrupted something in its performance*:idea:*
Did you (or somebody else) tinker with Google Chrome's files or like that - maybe trying to adjust some styles/user CSS? :sherlock: