a clean reinstall might do the trick. I guess there was something wrong with your virtual drive software. Perhaps it does not support x64 Windows properly.
What you could also try before getting ready to reinstall:
- uninstall all CD/DVD related software. Reboot.
- then uninstall the optical drives from device manager and reboot again
In order to check if there is no hardware issue, you can try to boot from your Windows CD (you need to "hit any key", so watch the screen), and then abort the setup process.
Also, you can perform a repair install instead of formatting and installing. See microsoft website for details, please - I am not familiar with Vista.