just tried to install the fglrx-update drivers on Ubuntu 13.04, and after the restart, I got X server but no menu bars, window decorations, etc.

lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
01:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Whistler [AMD Radeon HD 6600M Series]

unity --replace & output:

darkhole@devolo:~$ unity --replace &
[1] 2857
darkhole@devolo:~$ compiz (core) - Info: Loading plugin: core
compiz (core) - Info: Starting plugin: core
unity-panel-service: proceso no encontrado
compiz (core) - Info: Loading plugin: ccp
compiz (core) - Info: Starting plugin: ccp
compizconfig - Info: Backend     : gsettings
compizconfig - Info: Integration : true
compizconfig - Info: Profile     : unity
compiz (core) - Info: Loading plugin: composite
compiz (core) - Info: Starting plugin: composite
compiz (core) - Info: Loading plugin: decor
compiz (core) - Info: Starting plugin: decor
compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available
compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available
compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available
compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available
compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available
compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available
compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available
compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available
compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available
compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available
compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
compiz (core) - Info: Loading plugin: imgpng
compiz (core) - Info: Starting plugin: imgpng
compiz (core) - Info: Loading plugin: move
compiz (core) - Info: Starting plugin: move
compiz (core) - Info: Loading plugin: gnomecompat
compiz (core) - Info: Starting plugin: gnomecompat
compiz (core) - Info: Loading plugin: mousepoll
compiz (core) - Info: Starting plugin: mousepoll
compiz (core) - Info: Loading plugin: snap
compiz (core) - Info: Starting plugin: snap
compiz (core) - Info: Loading plugin: resize
compiz (core) - Info: Starting plugin: resize
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
compiz (core) - Info: Loading plugin: vpswitch
compiz (core) - Info: Starting plugin: vpswitch
compiz (core) - Info: Loading plugin: grid
compiz (core) - Info: Starting plugin: grid
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
compiz (core) - Info: Loading plugin: regex
compiz (core) - Info: Starting plugin: regex
compiz (core) - Info: Loading plugin: place
compiz (core) - Info: Starting plugin: place
compiz (core) - Info: Loading plugin: compiztoolbox
compiz (core) - Info: Starting plugin: compiztoolbox
compiz (core) - Error: Plugin 'opengl' not loaded.

compiz (core) - Info: Loading plugin: session
compiz (core) - Info: Starting plugin: session
compiz (core) - Info: Loading plugin: workarounds
compiz (core) - Info: Starting plugin: workarounds
compiz (core) - Error: Plugin 'opengl' not loaded.

Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0
Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0