915gm/945gm/XAA lockup with gray blocks when switching video mode

[Juan Pablo Salazar Bertin]

I'd like to add some things about this bug:

It has been reported also at https://bugs.freedesktop.org/show_bug.cgi?
id=10586.

After several debugs, I've determined that the laptop hangs in the following 
loop in file i830_driver.c:

   for(i = 0; i < 256; i++) {
      OUTREG(PALETTE_A + (i << 2), pI830->savePaletteA[i]);
   }

You can see full gdb output here: https://bugs.freedesktop.org/attachment.cgi?
id=11964&action=view
After the last line, the laptop hangs.