Solution : problem installing ubuntu with WUBI, installation halts at Busybox (initramfs) prompt

Are you trying to install Ubuntu/Xubuntu using WUBI? After running the wubi from inside windows and after reboot do you stuck at some point with this prompt?

Busybox v1.1.3 (Debian 1.1.1.3-5ubunu7) Bult-in shell (ash)
Enter help for a list of built in commands.
(initramfs)

I also got the same thing and was astonished. The solution is simple: From windows, after running the WUBI installer, replce "quiet splash" with "all_generic_ide" in the file g:\ubuntu\disks\boot\grub\menu.lst and reboot. Hope it works. (Here G: was the drive that is selected for Ubuntu installation, it may be different for you)

also, is your drive FAT32 formatted? make it NTFS.