Anyway, this problem appears to be flash independent because it seems to happen with just the simple blinky sketch. I wait with interest for the result of the SCK pullup test..
Mark.
No Mark, the code I mentioned is in the bootloader and gets executed on any watchdog reset. I'm not quite clear how this would happen on a simple power-up, but there are possible paths, e.g. Bootloader runs and uses a wdt reset to start app.
In any case this would explain why I never see the issue - given that I use a different bootloader.
So yeah - let's have a sck pull-up and a miso pull-up test.
Joe