Well, personally I don't like friendly error messages, if they were implemented, I think making them optional is essential, or Km might well loose a few users - pretty sure they aren't optional in IE. Personally I'd prefer them not to be added at all.
When IE uses them it for some reason insists on accessing MSN to display them too - which I'm not sure I like - also makes things slightly slower, and any delay, no matter how slow annoys the hell out of me
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