After I select an entry (Ubuntu) from the Grub menu, the screen goes to power save mode.
I could eventually get the screen asking me for the HDD encryption password by pressing Alt-F1 and then Alt-F7 (Alt-F7 alone did not work). Then I could enter my password and the boot process continued normally.
This behaviour (screen switching to power save) has occured since the upgrade from 14.04 to 14.10.
I have some non-standard disk layout (RAID, LVM, LUKS encrpytion), maybe it is related to that. I also had the "disfilter writes are not supported" problem, but could solve it with
I tried appending
nomodeset as explained here (i.e., I pressed "e" and then added it to the line which starts with
linux). Now the monitor did not switch to power save and I immediately got the password screen for unlocking the encrypted harddisk. But when I typed, no dots showed up, and nothing happened when I pressed enter. After switching screens, on Alt-F7 I saw the password as raw text (and nothing else). So this did not help at all, I would rather say that it's worse than before ...