Comment 89 for bug 551290

(Comes from bug #571567):
Same problem here:
I installed a vanila Ubuntu Lucid Lynx 10.04 and updated everything using apt-get.
Then I installed KDE and up to this point, everything works normal.
Then I downloaded a couple of login screen themes and switched my default theme with one of those.
Then trouble started. t first, I viewed the low res logo at boot, with some aliasing errors. The boot proccess stops there and then I can not even switch to console mode with Ctrl+Alt+F1, the computer is just frozen.
I tried a trick: inserted the ubuntu cd-rom on drive and hard-rebooted the PC, then choose "boot from first hard disk" option and then I could log in to mi KDE desktop.
I reverted my login screen theme back to the default one, and rebooted. Now I see a splash screen reading "kubuntu" but the computer freezes again, keyboard is blocked, etc, same as before.
My PC currently only boots when using the CD-in-tray trick.