This post is a bit old, but I was having a similar issue, and it seems the OP never got an answer which helped. Like I said, my situation was similar, but my monitor reported that it was
not optimal, and displayed nothing.
The menu was there, I know because I could arrow down and press Enter and the boot up would be different (i.e. 4 down was Windows on my PC). I did a little research and ended up updating
/boot/grub/grub.cf setting the line as follows:
Saved and rebooted. The menu now shows. Hope this helps.
Note: You have to
sudo to edit the file.