Hi,
The issue is in the VM and it occurs every time the option ROM is executed. Standard VGA text mode displays fine (ex. SeaBIOS version string and boot menu), but any sort of extended graphics mode (ex. live CD boot menu) tries to make use of the host memory area which corresponds to the stolen memory area of the physical device.
I'm wondering whenever we can just use seavgabios (and support standard vga modes only).
cheers, Gerd