After a recent installation of Kubuntu 15.04 using encrypted LVM, I have the following problem. When I boot the system, the pretty Kubuntu encrypted disk password screen appears, but when I type the password, it appears overlayed at the top-left of the screen rather than in the box. It is also not actually accepted as the password if I press enter.
This is with a fresh install of Kubuntu, and I've actually had the problem manifest on two different laptops. It can be worked around by using the recover mode menu which takes the password in pure text mode, but I'd obviously prefer that I not have to remember to interrupt GRUB at boot time.
If it's related, the recovery menu "box" that's displayed using graphics characters looks like it's using the wrong character set as well and shows as a series of strange accented characters rather than lines.
Edit: I've eliminated the need to go into the recovery menu by removing "quiet splash" from GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub. This allows the password to be entered in text mode, but not in the pretty Plymouth splash screen.