Common problems running compiz

I will run through the most common problems running COMPIZ with ATI drivers:

• Try runnign compiz as ROOT
  this may seems stupid, but solved a lot of issues
  $ killall compiz
  $ sudo compiz
  At lest, if it works, you'll know what direction you have to look.
  

• “desktop effects could not be enabled”
  if the desktop effects gui will raise this message, try running “compiz” inside a terminal, and see that it tells you.

• “Checking for Xgl: not present.”
  this message is not a real problem as it may seems, compiz tries other configs, so don't loose time trying to fix it. Go ahead on this guide instead

• “Another window manager is already running”
  this means exactly what it tells.
  Check inside “System preferences” → “Preferences” → “Sessions” if you have another wm running, for example: XCompMgr.
  In that case, kill it and try compiz again;
  $ killall xcompmgr
  $ sudo compiz

• compiz white screen
  After reboot, when you login in GDM, your desktop is just a white screen?
  Follow this other POST to get back to a normal desktop.

• compiz with no window decoration
  Your compiz has no window decoration? no window borders?
  This is mostly caused by compiz don't finding the needed files ...
  Open a termina and:
  $ killall compiz
  $ sudo compiz
  If this solved, you may need to check the System → preferences → Sessions and see what's wrong with the startup script.
  
  

• compiz with no window decoration [2]
  Another possible cause may be the Video Drivers you'r using. Check for the latest version !!! or look for another driver to use with a newer but similar video card to the one you have.