Most of the time I start the script I will get a 15 second countdown timer to shutoff with a "half-press shutter" cancel.
That's strange. There is no code in either script that will do that. And I can't think of anything else in CHDK itself that would do that.
"memory card error" will occasionally appear as well, but only while running these scripts.
It would be interesting to know what is causing that message.
Can you take pictures of your camera's screen (with a mobile phone maybe) so that we can see exactly what the count down and card error messages look like?
I have used two different SD cards, reformatted and re-ran "STICK" multiple times to no avail.
Any advice as to the problem?
Both scripts will produce log files as they run. I'm not expecting much here as I don't think this is script related but would you enable the logs, do some testing, and post the resulting logs here as attachments?
What happens if you try to run the simple interval.lua script that comes with CHDK's default install?