The reason for trouble at start-up can be because the digital comes up at an
unknown state if the clock is not applied before the power supply.
To prevent this trouble, you can apply a digital reset at power up to ensure
the digital is at a known state.
A digital reset can be applied by writing to the SPI Port Config registers.
Write to bit 2 in register 0x00 for a soft reset. Setting thethis bit activates
the default settings of all serial registers except 0x00, 0x09, and 0x0A. In
datasheet table 26 you can also find this information.
The second option is to ensure clock is applied to the device before power.