Plate chiller related off flavor

Hi to everyone!
I'm courrently having an odd situation to which i'm not being able to find an answer.
We have recently change our chilling method from a cooper counterflow chiller to a plate chiller (Duda diesel, 20 large plates). The thing is that since we stated using it our beers started to have ea particular off flavor, slightly salty and with a really strong biter and dry taste.
Any ideas of what could be happening?
Thanks to all!

Greetings tmuir - I have some questions regarding your issue:

1) did you buy your plate cooler new, or was it previously used?
2) how many times did you use it before you noticed the off flavors?
3) do you back flush the cooler after using it to cool wort?
4) do you filter or strain the wort prior to running it through the cooler?
5) is your wort pumped through, or is it gravity fed?
6) what are the sanitation practices you exercise with your plate cooler?

Sorry for all the questions, but my Blichman plate cooler has been on line now for three years with no issues at all.  So your problem is quite interesting to me.

So, I was dozing peacefully in the back row when the professor dropped a book. I jumped a foot out of my chair and as I was settling back to get some well-deserved rest, the professor said: "... So, based on what we have been discussing for the last ten minutes, it is clear that correlation does not mean one event caused the other. One event preceding another does not mean the first caused the second. You will see that concept on the test and in your research!"

Now that I'm awake, I'll add, "And, especially in brewing!"