I've been running 12.10 for ~(two weeks) now and have had my fair share of trouble with it. Of course, this has thought me a great deal of lessons of using ubuntu, the command line and Linux in general. It also sparked my interests in open-source/free software and why it is so precious. I've learned to respect the community and am actively learning my way through.
Now, last night I attempted to optimize my laptop power consumption and installed, amongst others, powertop. As far as I can recall, I didn't do anything dramatic to my system, except changing the power governor from ondemand to powersave.
This morning the system goes into a flashing cursor in top left after boot. At this mode I can't enter TTY-s using ctrl-alt-F(1-7). So, I reboot -> Advanced options for... -> ...(recovery mode) -> root and attempted to play with lightdm as was done here. Initially there was a problem with the /var/lib/dpkg/lock and /var/lib/apt/lists/lock . So I removed the locks. Then tried
and it worked (no error messages). Rebooted and started normally and this time even the cursor went fishing. So, no flashing, no I/O whatsoever (to a mortal).
Then, went back to recovery -> root and did some of the listed options, namely: check the file systems (fsck), update grub bootloader (grub). Tried to failsaveX and that didn't start either. So, back to root shell and
apt-get install --reinstall lightdm
I also set the power gov back to "ondemand". Also tried several other things, which are to my judgement, not worth mentioning.
So, quite desperate. Please give a pointer as to how to proceed.
SYSTEM SPECS: Ubuntu 12.10 on a DELL E6420 laptop. All worked out-of-the box with 12.10, with the occasional crash upon system update.
When I try
sudo service lightdm start
System goes back into black screen with no I/O option.
After some reading and testing, the problem emerged as wireless not working. So, connected to ethernet. Then run the same commands as above (udpated lightdm) and log-in screen appeared, but could not connect. Then, went back into tty1 and re-installed compiz and unity. Then reboot and BAM - works!
As to the many existing issues with Linux, I could, with my lately gathered understandings and skills, generalize the main cause of errors in Linux is the keyboard operator (aka ME).