I have a strange problem with a fresh installation of Lubuntu 15.04 (Ubuntu 11.04 was ok). Sometimes when I boot the computer the monitor goes in "No DVI signal" mode right after grub selection. However, if I unplug the cable and plug it again I can see Lubuntu booting! The same if I press some buttons.
If I push the reset button I won't have the no-signal problem but it will come back at the following boot.