You can search for this bug and it seems like it may be related to ecryptfs and is many years old.
The symptoms are that you return to the computer and the screensaver was active or the screen was asleep/black and it doesn't seem to come back. But you check by SSH the computer is running fine and are frustrated you'll lose your running programs and have to reboot.
There is a simple solution:
Ctrl + Alt + F1
Ctrl +Alt + F8
Ba........
This happened while trying to delete several thousand users from phpBB and basically corrupted the innoDB tables.
InnoDB: Page lsn 3 881164362, low 4 bytes of lsn at page end 881164362
InnoDB: Page number (if stored to page already) 86920,
InnoDB: space id (if created with >= MySQL-4.1.1 and stored already) 0
InnoDB: Page may be an index page where index id is 700
InnoDB: (index "tid_post_time" of table "phpBBdb2005"."phpbb3_p........
mod_status is a great way to track down the source of high CPU usage and to find what vhost/script is the cause of it.
It gives you a live view of bandwith usage, CPU usage, and memory usage broken down by domain/vhost and script/URI.
Enable mod_status
vi /etc/httpd/conf/httpd.conf
ExtendedStatus On
SetHandler server-status
Order Deny,Allow
Deny from all
All........
What this really refers to is gnome-volume-control-applet which is what controls the volume in the panel/indicator applet.
In Ubuntu 10.04 it is just the applet mentioned above, run that from the command line and it will start.
I lost mine when I removed pulseaudio trying to fix audio issues with Flash and Opera. It also removes the gnome-volume-control-applet from starting. *Ialso note........