My system:
Dell Precision T3500
nVidia Quadro NVS 295
Ubuntu 12.04 x86_64 (3.2.0-32)

Essential problem:
On boot my system won't get past the splash screen. I can switch to another virtual terminal and log in, I can also ssh from another system -- so it appears that the problem might be with the display manager. How can I diagnose and fix this problem?

More info:
From a VT I can issue sudo lightdm restart, and this will bring up the login screen and and I can continue from there. So I do have access to my system.

Update-manager recently updated a number of packages, including a bunch of x11 and xorg packages, some nVidia drivers, rpcbind, etc etc.

My boot log (if that is any guidance) says the following:

fsck from util-linux 2.20.1
fsck from util-linux 2.20.1
fsck from util-linux 2.20.1
fsck from util-linux 2.20.1
rpcbind: Cannot open '/run/rpcbind/rpcbind.xdr' file for reading, errno 2 (No such file or directory)

rpcbind: Cannot open '/run/rpcbind/portmap.xdr' file for reading, errno 2 (No such file or directory)

/dev/sda1: clean, 597650/1525920 files, 3963433/6103296 blocks
/dev/sda7: clean, 11/6406144 files, 450097/25608703 blocks
/dev/sda5: clean, 158323/1525920 files, 1886918/6103296 blocks
/dev/sda8: clean, 250089/107929600 files, 111088810/431689728 blocks
Skipping profile in /etc/apparmor.d/disable: usr.bin.firefox
Skipping profile in /etc/apparmor.d/disable: usr.sbin.rsyslogd
 * Starting AppArmor profiles       [80G 
[74G[ OK ]
Loading the saved-state of the serial devices... 
/dev/ttyS0 at 0x03f8 (irq = 4) is a 16550A
 * Starting ClamAV virus database updater freshclam       [80G 
[74G[ OK ]
 * Starting Name Service Cache Daemon nscd       [80G 
[74G[ OK ]
 * Starting modem connection manager[74G[ OK ]
 * Starting K Display Manager[74G[ OK ]
 * Starting mDNS/DNS-SD daemon[74G[ OK ]
 * Stopping GNOME Display Manager[74G[ OK ]
 * Stopping K Display Manager[74G[ OK ]
 * Starting bluetooth daemon[74G[ OK ]
 * Starting network connection manager[74G[ OK ]
 * Starting Postfix Mail Transport Agent postfix       [80G 
[74G[ OK ]
speech-dispatcher disabled; edit /etc/default/speech-dispatcher
 * Starting VirtualBox kernel modules       [80G 
[74G[ OK ]
 * Starting the Winbind daemon winbind       [80G 
[74G[ OK ]
saned disabled; edit /etc/default/saned
 * Starting anac(h)ronistic cron[74G[ OK ]
 * Stopping anac(h)ronistic cron[74G[ OK ]
 * Checking battery state...       [80G 
[74G[ OK ]
nxsensor is disabled in '/usr/NX/etc/node.cfg'
Trying to start NX server:
NX> 122 Service started.
NX> 999 Bye.
Trying to start NX statistics:
NX> 723 Cannot start NX statistics:
NX> 709 NX statistics are disabled for this server.
NX> 999 Bye.
 * Stopping System V runlevel compatibility[74G[ OK ]
 * Starting Mount network filesystems[74G[ OK ]
 * Stopping Mount network filesystems[74G[ OK ]
 * Stopping regular background program processing daemon[74G[ OK ]
 * Starting regular background program processing daemon[74G[ OK ]
 * Starting anac(h)ronistic cron[74G[ OK ]
 * Stopping anac(h)ronistic cron[74G[ OK ]