I left the sx260 and sx50 running at home while I took the G1X up Spencer's Butte for sunset. The G1X has never triggered the script interrupted error since the Lua update. When I got home, the SX50 display showed the interrupted error, and the SX260 was off with the lens extended.
Both cameras got the error about 10 minutes after I left. Usually, it takes longer. This time, I set a small metering area where clouds were moving by, so the shutter time was varying a lot. My smoothing routine limited the Tv96 changes to plus or minus 1. I suspect that the timing of an extra interrupt that occurs to close the shutter may be involved. That is, an interrupt in a function that isn't thread safe (or something). Perhaps this could be the Lua incremental garbage collector. Maybe it has something to do with the 2 Lua threads also.
Anyway, one of reyalp's new logs appeared for both cameras. I'm also including the romlog from the SX260, but the crash may not be significant. The time in the romlog is 2013:04:10 09:40:45. I have the camera clock in AM/PM mode, so if the time was 9 p.m. that would make sense. I had an external battery connected that switches itself off automatically, so I suspect the "crash" was just a sudden loss of power. I also included the script log, which shows the error code at the end. Everything looks normal in the script log until the error. The second "Lapser" number is the return value from resume(). I think it's just a pointer to the NULL error message string.
I don't know enough at this point to tell much from the new Lua logs, but every time one of my new "theories" is shot down, I learn a little more. Thanks!