In case you are using the textual boot screen (i.e., with GRUB_TERMINAL=console), the flag GRUB_HIDDEN_TIMEOUT_QUIET apparently has no effect. Instead, you should uncomment "hiddenmenu" in /boot/grub/menu.lst.
In case you are using the textual boot screen (i.e., with GRUB_TERMINAL= console) , the flag GRUB_HIDDEN_ TIMEOUT_ QUIET apparently has no effect. Instead, you should uncomment "hiddenmenu" in /boot/grub/ menu.lst.