Using 18.04LTS, and last month when it updated and needed to reboot to 'finish', it locked-up upon reboot and has been doing this ever since - I go to boot up, it gets to the blank screen where the mouse pointer shows up, and then the pointer freezes, the light for HD access goes out, and nothing is responsive - dead.... So, hold down the power button, reboot, and it goes to the purple page with the count down and list, defaults, and boots up fine... thankfully there's my VISTA64 laptop that works without all this linux grief, that I now have to depend on for daily work - and which btw works flawlessly (but no 'updates' to it to mess it up - too old for microslop) ~ sure wish linux did as well. Think I'll have to wipe drive and restore backup image to fix unless someone knows what is bugging this thing... maybe then just cut off updates all together as they just seem to cause problems so who needs them ~ so much for LTS?
FYI - The thing did a couple of updates since this issue popped-up, but none required to be rebooted to 'finish' nor did they fix the boot/reboot bug...
LATER - latest Ubuntu update just required reboot to 'finish' again... rebooted and hung-up frozen - hit power button, reboots fine using 'list' w/ timer of purple page. SEEMS TO BE HANGING EVERY OTHER BOOTUP
WORKAROUND: (FOR MY TOUGHBOOK)...When booting up hit 'esc' when the 'PANASONIC' splash-screen comes up to go see the BIOS terminal output - Next, when the menu to select CD/HD/USB comes up to boot off of, arrow down to 'HD' and hit 'enter' - finally, if the purple screen comes up w/o the Ubuntu menu, hit 'esc' to get it to come up, then hit 'enter' selecting the default, now hold down power button to reboot. THE NEXT time around it will not go to the blank purple screen, but rather to the purple screen with the Ubuntu menu ~ hit 'enter' when it does and it will FINALLY fully boot (ie not hang) :-\