I am using grub2 at the moment so can not test hidden menu but I have some suggestions
1) using the live cd...mount and edit that menu to put a # in front of hiddenmenu
2) your menu has a separate line for UUID. I have not seen that before.
I could be wrong...but here is a link of a recent ubuntu agreeing with me...its a wee bit hard to read but is very gui.
Note there is an overlap or overflow from one line to the next...so the line for kernel is showing as 2 lines ok?
a quick search shows an older menu but illustrates the issue clearer
you boot the live cd...mount the partition as previously discussed.
copy the first menu and rename its title...original
edit the original title...no uuid
and delete the entire line for uuid
3) while in live cd mode...lets check that the UUID is correct
try looking at
or use a terminal to try
blkid -s UUID
ls -l /dev/disk/by-uuid/
vol_id -u /dev/sda1
4) even if they are right....add a new entry
change the kernel line where it says root=uuid=string to root=/dev/sda1
and reboot to test if any work