Do u have system installed on harddisk already?answer this or do u tinkered with some files as root?if u can try installing alternate kernel or reinstall kernel if u got distro installed on hdd.
is init available. from a terminal ask "whereis init"
as with OP,irq problems are caused by a buggy acpi,it can be bypassed by appending options like acpi=off ,irqpoll on kernel line of grub.
if u can access distro in hdd -go to /var/log/messages and post the messages to *pastebin.ca and link here
also post the output of fdisk -l and explain if u tried partitioning on hdd after linux installed(sometimes partn numbers may change) do u have seperate /boot partn?
edit:Now i think i know the problem-as ur using fedora,it got LABEL=(disk label) in kernel line.edit ur kernel line in grub replacing
LABEL=/ by root=/dev/hdx where hdx is the partn number where Fedora is installed.Hope this helps.like LABEL in Fedora,Ubuntu uses uuid making difficult for n00b's figuring out what went wrong
