Some of my previous posts have described my experiences of running Ubuntu Linux on my daughter's Packard Bell OneTwo 'all in one' touch screen computer.
Ubuntu 11.10 was working fine, but updated it to 12.04 last night. No errors during update, and it was late when it finished so switched it off and went to bed. This afternoon she reported that she had to resort to booting Windows because Ubuntu does not work - she got a black screen that she left waiting for 5 min, before giving up and booting Windows.
From a quick fiddle booting in 'recovery mode' and trying the safe graphics option, I think it is something to do with the graphics hardware not working, but am going to have to investigate more....just lent her my laptop to do her homework for now....
Went through a few options that I found on the internet, but none seemed to be quite my problem. Also tried running 12.04 from a memory stick in case the upgrade had gone wrong, but it failed to work that way too....So I gave up - saved a selection of files from /var/log/ and re-installed Ubuntu 11.10.