We figured out the issue. We had a window that was being placed at position 0,0 of the monitor instead of within the parent NoMachine frame. I am guessing when NoMachine was attempting to render that window it could not interpret the correct location to place the window and crashed. What is interesting is that running the same code on a 6.0.66 Windows client does not crash NM. I wonder if this was something that was broken/fixed in the 7 version.
Ran a couple other times and got these results in nxtrace.log after crash:
#0 0x69a5220c libnxdifb.dll(fbBlt)
#1 0x695e4c34 libpixman.dll(pixman_image_create_radial_gradient)
#2 0x69a5eb5e libnxdifb.dll(fbCopyWindowProc)
#3 0x69b61adf libnxdifb.dll(miCopyRegion)
This is different from the original nxtrace but seems to be more common.