After restarting my ubuntu PC, I am getting a dialog window showing "Your system is running in low graphics mode" and after clicking on 'OK', I was prompted with three options 1. Run in low graphics mode for just one session 2. Reconfigure graphics 3. Troubleshoot the error 4. Exit to console login

When I troubleshoot the error, its showing the black screen with following lines which I remember:

we do not own /var/log/pm-powersave.log ....................................... couldn't write bytes: Broken pipe
....................................... ....................................... Starting System V runlevel compatibility

got strucked at this point.

Actually before restarting, I have changed the owner for all the files under the directory "/var/log" and "/var/lib". Is there any relation with the above issue. Please help me out to resolve the issue. Its urgent.