Under Windows 7 64bit, with a Phenom II 940 CPU on an MSI DKA790GX motherboard, the host will BSOD randomly when running VirtualBox, with the BSOD KMODE_EXCEPTION_NOT_HANDLED.
This is mentioned in the event log: The computer has rebooted from a bugcheck. The bugcheck was: 0x0000001e (0xffffffffc000001d, 0xfffffa8003f6f1d0, 0x0000000000000002, 0x0000000002b99500). A dump was saved in: C:\Windows\MEMORY.DMP. Report Id: 061609-15022-01.
From googling the first parameter of the 0x1e bugcheck, it seems to be related to Virtualbox.
This seems to be related to: http://vbox.innotek.de/pipermail/vbox-trac/2007-September/106534.html.
Because the guest is 64bit, AMD-V must be enabled. However I will try with Nested Paging off tomorrow. This did not occur on an Athlon64 X2 4800+ (Windsor) on an ASUS M2N motherboard with Nested Paging disabled due to lack of support.