Fedora: Hang with "Trying to unpack rootfs image as initramfs.." during installation

I crated a new virtual machine which ran Fedora 15  using Oracle Virtualbox.


During installation, this process was in hang in the step of "Trying to unpack rootfs image as initramfs..". 


VirtualBox is used to set 256MB of memory for a new virtual machine. I changed memory to more than 700MB. I finally worked.


According to Fedora documentation, it recommends hardware specification like: 
for x32
  - Recommended for text-mode: 200 MHz Pentium Pro or better
  - Recommended for graphical: 400 MHz Pentium Pro or better
  - Minimum RAM for text-mode: 256 MB
  - Minimum RAM for graphical: 640 MB
  - Recommended RAM for graphical: 1152 MB
for x64
  - Minimum RAM for text-mode: 256 MB
  - Minimum RAM for graphical: 640 MB
  - Recommended RAM for graphical: 1152 MB




Reference site: 
1. http://www.howtoforge.com/how-to-upgrade-from-fedora-14-to-fedora-15-desktop-and-server
2. http://docs.fedoraproject.org/en-US/Fedora/15/html/Release_Notes/sect-Release_Notes-Welcome_to_Fedora_15.html