Comment 119 for bug 571707

@luojie-dune I updated yesterday (Ubuntu Lucid) and noticed that on re-boot, the grub menu started showing up again, even though I had edited the configoration files to hide it. Clearly a recent update meddled with those files, without asking the user. I would imagine that is your issue to. If you boot up your PC using a LiveCD or USB and then read through the Grub conf files, it might fix your issue.