I've been running Ubuntu 12.04 LTS 64 bit with ulatencyd for months now and after rebooting yesterday, I hit a very hard to diagnose kernel crash. It seemed that random processes (usually Xorg, sometimes apache2, mysqld etc.) caused kernel BUG and PANIC triggers. After trying all the kernels I had installed it got clear that the problem was not caused by kernel version.
I finally was able to detect that the problem was caused by ulatencyd doing something early in the boot process that caused kernel to crash. I fixed the problem by adding "exit 1" at the start of the /etc/init.d/ulatencyd script to prevent normal startup of ulatencyd without uninstalling it.
The system had been running for two months before the restart so ulatencyd had probably collected lots of data during that time.
My guess is that ulatencyd causes some kind of race condition in the kernel early in the boot process that causes kernel crashes.
I'll attach a couple of photos of the kernel crashes.
ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ulatencyd 0.5.0-4ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-35.55-generic 3.2.34
Uname: Linux 3.2.0-35-generic x86_64
ApportVersion: 2.0.1-0ubuntu15.1
Architecture: amd64
Date: Wed Dec 19 10:10:37 2012
InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120823.1)
MarkForUpload: True
SourcePackage: ulatencyd
UpgradeStatus: No upgrade log present (probably fresh install)
mtime.conffile..etc.init.d.ulatencyd: 2012-12-19T10:06:56.904449
Additional info: I was able to boot into "recovery mode" and diagnose the system from there. However, trying to run normal boot resulted in kernel crash every time (I booted about 30 times while trying to fix the system). The crash occured usually before the purple "Ubuntu" boot screen was visible but one the system crashed in the lightdm greeter and I was able to move the mouse cursor and move focus to password input before the crash. I guess that the exact moment of the crash was depending on what ulatencyd was doing during startup and during that boot, ulatencyd was running slightly later than usual.
The system is installed on Intel 320 series SSD so the actual boot is pretty fast. My monitor is quite slow to display the image after resolution change so I'm not sure what the system was trying to display the moment the crashes occurred.