Ubuntu 11.04 fresh install - "Input signal out of range" or "Mode not supported..."
Solution 1:
I had a machine running Kubuntu 11.04 that suddenly started to do this last week - the fix was:
Wait for the invisible grub menu to timeout and the PC should eventually boot - or try pressing ENTER on the 'blank' screen and wait for Linux to boot
Open a terminal window and sudo vi /etc/default/grub (or use your favourite editor)
Find the line that starts #GRUB_GFXMODE=640x480 (or similar)
Insert the following on the next line: GRUB_GFXMODE=1024x768
Save your changes
Enter the command sudo update-grub
Reboot and see what happens!
If you want you could try another resolution such as 1280x1024, but 1024x768 gave me a suitable display.
PS: if this turns out to be more than just the boot menu, have a look at this Ubuntu Wiki page: https://wiki.ubuntu.com/X/Config/Resolution#Resetting_an_out-of-range_resolution