I wouldn't be surprised if there were a driver bug, since dynamic linkage doesn't get a lot of usage. You can find out for sure by running with the REF device, and seeing if that produces the correct behavior.
Thanks !! that was a great idea !! .. and the result is that with using a REF device i get the expected behavior ! Which means that this is a DRIVER BUG!
So if anyone has the same problem and stumbles on this thread , check your drivers
here are my specs (which are buggy) : Driver : NVIDIA Driver Version: 285.62 WHQL Driver Release Date: 2011.10.24