Hello, I have installed Stradivari, and it works nice in the Kontakt player (very good with the Finale2007), but in the Kontakt2, full version, it only gives a very short clear sound when a key is pressed, and then the sound becomes only a noise, as if it were suddenly damped.
It seems your Strad in Kontakt 2 doesn't properly receive CC#11 (Expression) which is vital, since it controls sustain level and tone colour (and probably other factors, too). What you describe is the typical case when CC#11 is absent.
Do you send CC#11 from Finale to your Kontakt Player, then, since it works for you? Or do you play expressions live, using a pedal or slider for CC#11?
If you insert Kontakt 2 in exactly the same way as Kontakt Player, it should work the same way.
I use the Strad only with Finale. And the curious fact is that I can open the Player and the K2 at the same time, and the result is the same: with the former, ok, the other, no.
I forgot: I use the PC, have done all the registries of the Strad and K2, and have downloaded all the recent patches and updates.
Make sure you're sending some kind of CC#11 (EXPRESSION) message, otherwise notes will sound just the way they are sounding for you. You say it's working fine in Finale, that might be because Finale is sending expression messages (that is CC#11 commands).
If you got a midi controller and an expression pedal (volume pedal), use the pedal while hitting keys and you'll see everything will come back to normal. If you don't have a pedal, try assigning some controller, like the modulation wheel, to play the role of the expression pedal. Hope everything turns out just fine!
PS.: Oh, there's one more thing to consider. Check out if you by any chance you didn't hit any of the Switch keys. They change the way the note sounds. Some keys will really make no sound come out at all!