I have been having a few reliability issues with the optiboot source code included in the Arduino IDE - which I used to compile a special bootloader for the regulator project:
So today I refreshed the complied bootloader using the latest source code from optiboot source repository: https://code.google.com/p/optiboot/
The resulting .HEX file is found under the Ardino Libs tab above, look for the 'SmartRegBoot' subdirectory - and follow the instructions in the blog link at the beginning of this post.
This refreshed optiboot still is configured for 8Mhz, 57600, and no-LED flashing. With my limited trials, I have found it to be a bit more stable...