Just had to reboot my computer, made a test program (ie removed my extraneous stuff), and - doesn't do it anymore.
Memory counts down to about 200 bytes, then pause - starts off at 15k again, but no reset.
Can't explain it. I am still trying to get an I2C object to persist between events (with no luck), so maybe something I did there was causing the resets.
I'll let you know if I figure out what is going on.