Hi Folks: I have had the exact same issue the last few days. I hadn't flown my trusty CS 757 in a while, so two nights ago I set up a flight from CYUL to CYHZ. I used ASN for weather, FSX in DX10.
About 10 minutes into the flight the plane became uncontrollable - violent pitching and rolling,  in auto or with the AP off, eventually crashing into the ground.
I repeated the flight again last night using a well known 737-800. No issues,  lovely flight (lousy landing but that was my fault).
I redid the flight again tonight once again using my CS 757. Once again, at approximately the same time frame, the plane became almost uncontrollable. At this point, I shut down ASN and started up OpusX which I also have. The 757 settled down and flew correctly. I changed ASN settings from realistic to easy, shut down OpusX and restarted ASN. The plane became violently pitching and banking again - but not quite as bad as previous. I shut down ASN, and restarted OpusX, and the remainder of the flight was fantastic.
To the great relief of the deathly ill passengers, I nailed the landing (calm winds always help).
It appears to me as mentioned previously that ASN does seem to dislike the CS757.