Compositing Woe in FXa

[kwhiskerz]

I have 2 computers, both running Fedora X alpha (and current with 
the latest updates from Rawhide and Livna-development), both 
using on-board Intel graphics.

On the desktop, when I enable kwin's OpenGL compositing, all is 
fine. On the laptop, the same choice works just great for the 
session, but when I log out and back in or reboot, X hangs and locks 
both the keyboard and mouse, and refuses to log in.

I have tried various grub kernel boot line options, such as removing 
rhgb, using nomodeset, or even enforcing=0, but none produced 
any difference. I am forced to edit kwinrc after booting to run level 
3, setting compositing to false. Login is then possible.

Both computers have minimal xorg.conf files in place, as per recent 
threads, namely Option "AllowEmptyInput" "off" in the ServerFlags 
section, as no keyboard was available on either computer without 
this tweak.

So, why do these 2 computers react differently, despite both using 
Intel graphics and having the same configurations? How can I use 
OpenGL compositing on the laptop without disabling it every time 
before logging out and re-enabling it once logged in?
_

[FX looks super :) by the way! Pulseaudio doesn't crash all the time, 
KDE 4 is colossal, Firefox and OpenOffice have had their wrinkles 
removed, their icons blending into the desktop theme nicely...]