I've seem to have found a solution for this. I don't have the slightest explanation, but it seems that adjusting the PC monitor refresh rate fixes this issue. For me, setting it to 59hz instead of 60hz fixes the problem (I don't have any other refresh rate options). Apparently, Nestopia does not like the 60hz... who knew?

Although I can't test anything lower than 59hz or higher than 60hz, I'm sure that other refresh rates will work just fine. This fix (for some) comes with a very minor cost: vsync feature in windowed mode will not work. However, it will still work in fullscreen mode.

I hope this discovery helps those who are having similar issues.

Notes: Tested with the latest unofficial Nestopia build at this time, it can be assumed that this fix works for the previous official builds.

Disregard this thread. It took until now for the sound to start desyncing again. Guess there is really nothing the user can do about this problem. It's a shame, because I thought I had finally found the solution to the problem.

If there is a mod around, please delete this thread.

Okay, I got to the bottom of this (for real, this time).

After extensive testing for a few weeks, it seems that 1.36 does not have any issues with the sound at all. No lag, so crackle, nothin'.

For builds after 1.36, set the speed in the timer options to 59 or 61 as this seems to fix it (not necessary for 1.36). I haven't tested this as much as I had trying out the previous builds.

I suspect that the sound issues are a result of something going screwy with the timer, or maybe the sound core got messed up somehow. Seems like more of a timer issue, really.

I confirm this:
http://forums.bannister.org/ubbthreads.php?ubb=showflat&Main=6223&Number=63263#Post63263

I've also noticed issues with nestopia sound, even on 1.36. Changing the speed does not solve the problem. If you listen to the sample clips below (1.40), is this the same issue?

http://dl.dropbox.com/u/239789/nestopia_shatterhand.mp3
http://dl.dropbox.com/u/239789/nestopia_tmnt2.mp3

Hi,

I'm just checking in to see what's happening with this issue. Changing the speed to 59 or 60 (or anything else for that matter) does not solve the problem, and I do have the same problem in 1.36. I've been unable to play NES games on this machine for a year or more, ever since I upgraded to Win7, because of the sound problem. The unofficial 1.42 version still completely freezes my computer if I enable the high-precision timer, even if I physically remove my sound card and uninstall the drivers.

Is this really the state of NES emulation right now? Nestopia is completely unusable, there are no comparable emulators, Martin Friej has apparently joined Martin Korth in limbo, and everyone else has given up.