Hi Karsten,

please check:

1.
Was something connected to the SPI ports (P1.5, P1.6, P1.7), which can generate pulses ?
Maybe it can help to use pull up resistors.

2.
Was the reset circuit right selected for the minimum VCC voltage of the micro ?

3.
Was the crystal working good, e.g. start to oscillate fast enough until reset was done ?

4.
Try to set the lock bits or disable the RCEN fuse to see, if the flash was erased nevertheless

5.
Was the whole flash erased or only some bytes ?


Peter