Yes, I do see HALT3 at the right corner of WinUAE windows. At first, I thought that error message was displayed on the Amiga screen itself - sorry about the confusion!
I am running AmiKIT X on Windows 10 Enterprise 2016 LTSB. My setup is as follows:
8 GB RAM
NVIDIA GeForce 970 GTX
Sound Blaster Z
DualShock 4 with Sony DualShock 4 Wireless Adapter
I am not sure whether DS4 could be the culprit here - sometimes turning off DS4 from WinUAE game port settings does the trick and I can reboot just fine. However, there are times this doesn't work - could be just a coincidence.
Please let me know any additional details (or maybe logs?) you may need. It has been years since I last touched AmiKIT or Amiga emulation in general so I can be a bit rusty. Just lead the way and I'll be happy to assist!
Edit: Not sure if it is relevant but there are 4 other sound devices other than the Sound Blaster - 3 monitors (1 HDMI + 2 DVI) and the DS4 sound device. Also, only 1 monitor is turned on even though Windows detect other monitors as display and sound playback devices.