[gutsy] Broken visualization enabling fglrx

Once the 3d driver has been set and enabled correctly, the screen flickers with any application that uses graphics.
For example, running totem-xine from the terminal results in this kind of error:
~$ totem
The program 'totem' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadMatch (invalid parameter attributes)'.
  (Details: serial 76 error_code 8 request_code 140 minor_code 17)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

Running totem-gstreamer or any other video player, causes the screen flickering, even enabling any screen saver causes the same issue, making the system almost unusuable for any purpose.
This issue does not depend on compiz: using metacity instead of compiz doesn't solve the problem.
I've an ATI Radeon Mobility X1400, on an Ubuntu Gutsy.