Hi guys, Joel from Frozenbyte here. If both games have the stutter, then it points to a driver issue probably. Trine 1 was generally quite stutter-free (except low fps which may have been caused by antialiasing - later versions have slightly faster AA), and Trine 2 has different kinds of rare stutters (usually applied to the whole frame, not just a specific object)...
This sounds very weird though, haven't heard of it before. I can think of two non-hardware reasons though - PhysX, and corrupt game files, or combination of both. So first try to re-download the entire game (delete and download), and then see about reinstalling PhysX. If it still doesn't help, then graphics drivers is next (and sometimes that's a bit difficult with the NVIDIA drivers when PhysX is thrown into the mix). I'll also PM you an alternative suggestion which probably won't help though.
We don't distribute a 64-bit version of the game btw, 32-bit is what everyone has. It shouldn't have any issues on 64-bit machines. (This is due to a few reasons, and might change in the future.)
And yeah I may not stumble upon here again so the Steam Forums
is the best way to get in touch.
- Joel, Frozenbyte team, developers of Trine & Trine 2