Uninstalling fglrx leaves OpenGL broken

[cygnus]

Quick summary:

$ glxinfo
glxinfo: error while loading shared libraries: libGL.so.1: cannot open shared object file: No such file or directory

$ sudo ldconfig -p | grep libGL.so.1
# no output

Details:

on Dell Vostro 3450. has Unity, happy, but greedy:

$ 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: ATI Technologies Inc NI Whistler [AMD Radeon HD 6600M Series] (rev ff)

thinks, oh cool, let's try using the Radeon card!

$ jockey-text -l
xorg:fglrx_updates - ATI/AMD proprietary FGLRX graphics driver (post-release updates) (Proprietary, Disabled, Not in use)
xorg:fglrx - ATI/AMD proprietary FGLRX graphics driver (Proprietary, Disabled, Not in use)

$ jockey-text -e xorg:fglrx

restarts.
system loads, but Unity looks bad ("cheap" animation on Super+S, and Super+W, no transperancy on the left dock, etc).

$ glxinfo
name of display: :0.0
X Error of failed request: BadRequest (invalid request code or no such operation)
  Major opcode of failed request: 155 (GLX)
  Minor opcode of failed request: 19 (X_GLXQueryServerString)
  Serial number of failed request: 12
  Current serial number in output stream: 12

$ sudo ldconfig -p | grep libGL.so.1
 libGL.so.1 (libc6,x86-64) => /usr/lib/fglrx/libGL.so.1
 libGL.so.1 (libc6) => /usr/lib32/fglrx/libGL.so.1

thinks, ok, maybe Radeon HD 6600M is not fully supported yet.

$ jockey-text -d xorg:fglrx

restarts.
now seems like Unity does not start al all! (no docks)

$ glxinfo
glxinfo: error while loading shared libraries: libGL.so.1: cannot open shared object file: No such file or directory

$ sudo ldconfig -p | grep libGL.so.1
# no output

thinks, oh boy...

[cygnus (itamar-benzaken)]

although ugly, it was solved by:

$ sudo apt-get remove libgl1-mesa-{glx,dri}

and then

$ sudo apt-get install ubuntu-desktop