Authentication token manipulation error when changing root password from recovery mode

When booting into recovery mode, filesystem won't be mounted as read-write and therefore when attempting to change the password it won't work. To proceed we'll just have to remount the / as read-write by issuing the following command.

mount -rw -o remount /

How to disable plugin container for computers with very few CPU resources.

I am running a laptop which has a very small CPU and therefor when playing flash videos in the web browser, plugin container process gets to high and the video gets stucked.
A workaround we can do to minimize the resource consuming of the plugin is to disable the wrapper used by Firefox to play videos (plugin-container).  It is intended to jail a video into a process to avoid the hole firefox crashing under some unexpected condition. To do so we just have to tune a firefox option:

1. Enter about:config in your address bar
2. Search for dom.ipc.plugins.enabled
3. Set their values to false

And you are done.