Proved or proven?

[bradsmissus]

The sentence I want to write is

"This has often proved/proven to be counterproductive"

Which one is correct or is there a better word?

BTW - shouldn't this topic be moved to education?! I have learnt more from you lovely pedants than I ever did at school!!!! (Exaggeration emoticon!)

a thing is proven, ie, a proven remedy, so proven is an adjective.

You might consider" it has often been shown to be counterproductive."

gives you a bit of get-out clause.

Yes, things are proven. So it has proven to be counterproductive.

OTOH people have proved it to be counterproductive - because then you're using a verb to describe what people have done.