current/amd64 randomly shuts down after a few minutes when running under VirtualBox (ACPI problem?)

[Tobias Nygren <tnn%NetBSD.org@localhost>]

Hi!

For some reason -current decides that the power button has been
pressed after a few minutes and shuts down. Normally I'd suspect bad
hardware but since this is a virtual machine I'm not sure what to think.
Here is what I managed to grab with a screenshot when it happened after
around 4 minutes of uptime:

ACPI Error: No installed handler for fixed event - PM_Timer (0), disabling (20160422/evevent-325)
ACPI Error: No installed handler for fixed event - RealTimeClock (4), disabling (20160422/evevent-325)
ACPI Error: No handler or method for GPE 01, disabling event (20160422/evgpe-836)
ACPI Error: No handler or method for GPE 03, disabling event (20160422/evgpe-836)
ACPI Error: No handler or method for GPE 04, disabling event (20160422/evgpe-836)
ACPI Error: No handler or method for GPE 05, disabling event (20160422/evgpe-836)
ACPI Error: No handler or method for GPE 06, disabling event (20160422/evgpe-836)
ACPI Error: No handler or method for GPE 07, disabling event (20160422/evgpe-836)
acpivga0: connected output devices:
acpivga0:   0x0100 (acpiout0): VGA Analog Monitor, index 0, port 0, head 0
acpi0: entering state S3

-Tobias