said by chrisretusn:
I got both the KDE and GNOME 3 Fedora 18's to install on VirtualBox with no problems.
It must be something specific with my work laptop. I gave it 2 gigs of RAM, 64 mega of video ram, and 40G of hard drive space all on the latest release of Virtualbox, 4.2.6. This is a 64-bit machine with a quad-core Intel I7 processor and virtualization turned on in the bios. The host OS is Ubuntu 12.04 64-bit.
I'm going to try again on my home PC.