Any idea how to prevent this from happening again? I don't have anything plugged into the USB, does it still try to send data over USB with nothing connected?

Building a new printer and my first one using a Duet Wifi

While printing off the SD card, I've had it reset two or three times randomly now. I do not think it is the G-code as the first time I reprinted the same file perfectly fine.

[[language]]
M122
=== Diagnostics ===
Used output buffers: 3 of 32 (13 max)
=== Platform ===
RepRapFirmware for Duet WiFi version 1.19 running on Duet WiFi 1.0
Board ID: 08DDM-9FAM2-LW4SD-6JTD8-3SS6N-TMYHZ
Static ram used: 21176
Dynamic ram used: 95976
Recycled dynamic ram: 1632
Stack ram used: 1304 current, 4992 maximum
Never used ram: 7296
Last reset 00:10:21 ago, cause: software
Last software reset reason: User, spinning module GCodes, available RAM 3224 bytes (slot 4)
Software reset code 0x5003, HFSR 0x00000000, CFSR 0x00000000, ICSR 0x0040080f, BFAR 0xe000ed38, SP 0x2001f504
Stack: 00434fcb 00008196 ffffffe9 00051051 00081111 40080000 00008196 20003688 0042fceb 004338b0 61000200 42eeea80 00000000 00000000 00000000 00000000 00000000 4b5c3d5e
Error status: 0
Free file entries: 10
SD card 0 detected, interface speed: 20.0MBytes/sec
SD card longest block write time: 0.0ms
MCU temperature: min 28.3, current 28.5, max 28.9
Supply voltage: min 24.1, current 24.2, max 24.5, under voltage events: 0, over voltage events: 0
Driver 0: stalled standstill
Driver 1: stalled standstill
Driver 2: stalled standstill
Driver 3: stalled standstill
Driver 4: standstill
Date/time: 2017-08-29 02:39:06
Slowest main loop (seconds): 0.005859; fastest: 0.000061
=== Move ===
MaxReps: 0, StepErrors: 0, FreeDm: 240, MinFreeDm 240, MaxWait: 0ms, Underruns: 0, 0
Scheduled moves: 0, completed moves: 0
Bed compensation in use: none
Bed probe heights: 0.000 0.000 0.000 0.000 0.000
=== Heat ===
Bed heater = 0, chamber heater = -1
Heater 1 is on, I-accum = 0.0
=== GCodes ===
Segments left: 0
Stack records: 1 allocated, 0 in use
Movement lock held by null
http is idle in state(s) 0
telnet is idle in state(s) 0
file is idle in state(s) 0
serial is idle in state(s) 0
aux is idle in state(s) 0
daemon is idle in state(s) 0
queue is idle in state(s) 0
autopause is idle in state(s) 0
Code queue is empty.
Network state is running
WiFi module is connected to access point
WiFi firmware version 1.19
WiFi MAC address 5c:cf:7f:ef:4d:3e
WiFi Vcc 3.16, reset reason Turned on by main processor
WiFi flash size 4194304, free heap 39032
WiFi IP address 192.168.1.165
WiFi signal strength -65dBm
HTTP sessions: 2 of 8
Socket states: 2 0 0 0 0 0 0 0
Responder states: HTTP(1) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0)

I might try 1.19.1 tomorrow. Too late to do anything now.