This is what I had to do. I assume you're trying to install from the original installation disc?
At first attempt, the Windows Configuration Page is created with the Virtual VM. From the configuration Page, go into the Configuration Editor (double-click on "Configuration").
Go to Options > Booting tab and change the boot sequence from "Hard drive, CD-ROM, Floppy" to "CD-ROM, Hard Disk, Floppy". After the complete installation, be sure to change this back.
Try the Windows installation again. It might work at this point. It didn't for me and for a lot of other people. It will load the drivers and when it tries to start Windows, I got a "SESSION3_INITIALIZAION_FAILED" error. Be sure to watch this because this screen appears for about only 10 seconds before it disappears.
At this point, many have tried creating a disc image of the installation disc and installing from that. If all else fails, you may have to do that, but I didn't want to.
I got a hint from someone elsewhere on the net, that maybe the disc needed to be cleaned, because it certainly couldn't have been bad. I had a brand new disc, but what the hey. I brushed off all dust particles (there were only a few) and made sure there were no smudge marks on both the top and bottom of the CD, and inserted it back into the drive. Maybe reseating the disc helped, but whatever the case for the sensitive drive, it was able to read this disc now, and I was able to install.