QEMU-KVM Black Screen28 Sep 2010
I upgraded one of our servers yesterday, including an upgrade from the Debian Stable kvm72 package, to the Debian Backports qemu-kvm version 0.12.4, whereon I could no longer start our Windows Server 2003 virtual machine. As soon as the machine started, it locked up completely with just a black screen, and had to be terminated with a kill -9 signal.
After a considerable time spent googling without any success, I decided to upgrade the Kernel from 2.6.26 to the backports 2.6.32 and normal operation was restored. I mention this only in the hope that the next person who googles qemu-kvm black screen might be saved a considerable time searching for the solution!