By default, the MicroZed receives power from both the micro-USB and the active board power supply. For more details, see section 2.10.1 of the MicroZed HW User's Guide. This can cause several problems:
The recommendation is to remove D4 and D9 diodes and replace D9 with a short. This disabled powering from USB (D4) in favour of the external power supply (D9).