This is not quite predictable, but this has happened to me few times every day for about a week now, so I think it's worth reporting. I can also easily reproduce this in less than one minute as well, if you need more information. On 5.4-RELEASE: Take an USB memory, plug it into your system, wait until information gets written on console about it, then run camcontrol devlist, then unplug the device. Repeat for a few times and at some point the system crashes. I think that possibly devd is required for this to happen as well, as I once tried to reproduce this in single user mode without success. The crash happens in a bit different situations, but here is an incomplete stack trace of my latest crash: (I'm writing these on piece of paper, and I'm lazy, so please tell, if more info is necessary, and I'll crash my system again) fault code: supervisor read, page not present pid 640(camcontrol) tid 100071, td 0xc1d22190 strncpy (d18da9bc, d00006, 10) at strncpy+0x14 xptedtbusfunuc xptbustraverse xptedtmatch xpt_action xptioctl spec_ioctl spec_vnoperate vn_ioctl ioctl syscall Xint0x80_syscall I haven't tried other devices than USB memories, and I've only tested this on 5.4. Juho