I have this problem with my pc:
[ 0.545187]ACPI PCC PROBE FAILED. STARTING VERSION 219
[ 240.096017] INFO: task systemd-udev:376 blocked for more than 120 seconds.
[ 240.096060] Not tainted 3.19.0-15-generic #15-ubuntu
[ 240.096097]"echo 0> /proc/sys/kernel/hung_task_timeout_secs" disables this message.............
Well, the message duplicates, and the OS doesn't start, so I had to reboot my pc. However the problem appears periodically, I hope someone can help with this.