Which is correct: "bored of", "bored by", "bored with"?

I have been asked by a young friend, "Which is correct: bored by, bored of, or bored with?" My instinct is to say that "bored of" and "bored by" are fine, but "bored with" sounds like she is being bored alongside someone else who is also bored. My trusty Dictionary of English Usage has failed me. Any thoughts?

All are correct!!

I'm bored of being the winner!

I'm being bored by my colleagues!

I'm totally bored with my tasks at work!

Yet another usage, I'm bored to death!! ;)

They're just alternative prepositions - no "grammatical rule" dictates that any one in particular is right or wrong.

Having said that - in my opinion "bored of" sounds "uneducated", so I'd avoid it in any but the most informal contexts. I think there's no real justification for this, but here's my evidence that most people agree with me...

On the Internet at large, Google reports 25M instances of "bored of" - against 17M for "bored with", and only 7M for "bored by". The difference between the Google Internet and Google Books is primarily down to the fact that the relative newcomer "bored of" is still primarily a spoken usage, not considered quite "proper" in written contexts.

TL;DR: Safest is "with" - "by" is okay, but avoid "of" if you want to sound like a careful speaker.