Markus,
I'm trying to understand the timing. Are you saying the board has to be up and running for a long period of time (> 1hr) and then when you power cycle it the DSP load fails? Or is it that the board has to be off for a long period of time and then when you power on the board the DSP load fails?
In either case, I understand that the same firmware script is used to load the DSP with the same executable during the Linux boot sequence. Is this correct?
Are there trace logs you can look at? I'm not familiar with the SDK but on some systems you can mount a debug file system and look at DSP trace logs.
Another idea is to check the log events on the DSP. After the failure occurs, use CCS to attach the DSP and look at its log buffer. Maybe you will find some clues.
I'm hoping someone on the SDK team will help out.
~Ramsey