Hi, I have fresh install of Ubuntu 13.10 with full disk encryption enabled, when starting just after grub Ubuntu freezing on purple screen, after further investigation removing 'splash' from grub solved the problem(nomodeset changes nothing).
Wanted to debug it so added plymouth:debug and drm.debug=0x4 parameters (plymouth:debug alone wasn't working and was causing same freezes as before) and then it looked fine - was asked for cryptsetup password by plymouth, but wasn't able to find anything useful in either plymouth debug log or dmesg(attaching both).
I noticed that enabling cpu's build in graphics card(so having both nVidia and Intel enabled at the same time) making it work sometimes(but it's very random), but it never works on nVidia only other that without splash or with options mentioned above.
It may be somehow related to #939283 maybe, that would explain it working sometimes when Intel graphics is enabled