Comment 6 for bug 276311

You don't need to reinstall the system, remove compiz or even deactivate it to solve the problem. Here are three ways of doing this. All of them can start with:

1. In the login screen, select Options > Select Session...
2. Choose "Failsafe Terminal" and press "Change Session"
3. Write your username and password, and click the info window away

Then:

Method A (if you use the GConf backend for compiz, which is the default):
--------
4A. At the terminal, type
    gedit .gconf/apps/compiz/general/allscreens/options/%gconf.xml
    and press enter
5A. Delete these three lines:
      <li type="string">
        <stringvalue>mag</stringvalue>
      </li>
6A. Click on save
7A. Select File > Quit, type "exit" in the terminal and press enter. Then login as usual.

Method B (if you use the GConf backend for compiz, which is the default):
--------
4B. At the terminal, type
     gconf-editor
     and press enter
5B. Navigate to apps/compiz/general/allscreens/options on the left pane
6B. On the right pane, double-click on "active_plugins"
7B. Select "mag" in the list, click "Remove" and press OK
8B. Exit gconf-editor using the File > Quit option, type "exit" in the terminal and press enter. Then login as usual.

Method C (if you have ccsm installed, which it is not by default)
--------
4C. At the terminal type
    ccsm
5C. Deactivate the Magnifier plugin.
6C. Exit ccsm at the "Close" button, type "exit" in the terminal and press enter. Then login as usual.

You can do something similar if you use the flat-file backend, etc. The point is: change the compiz configuration without having started compiz.

Hope this helps people with this problem.