X locks up with Intel Q45/Q43

[Alessandro Boggiano]

Hi all,
I have a big problems with my Dell Optiplex 780 and KDE 4.2. (FC10).

Here the beahvior:
If I don't use any xorg.conf file, and let the system probes the hw,
the monitor enters in power save and the computer locks up (not always 
but VERY OFTEN).
(no answers at all, I can't even ssh in it!)

So I used system-config-display in order to generate a xorg.conf file.

Everything works fine until I enable  desktop effects.
The problem is that the graphic is really choppy: often,
I have to close and reopen  a window several times in order to see it 
correctly.

I have read this
http://userbase.kde.org/GPU-Performance#Desktop_Effects_causes_random_freezes
and I tried to add le line:
Option "AccelMethod" "EXA"
but no luck at all!

And right now,while I'm typing, X is locked up and I can see (in ssh) in 
/var/log/Xorg.0.log a lot of these:

[mi] EQ overflowing. The server is probably stuck in an infinite loop.
[mi] mieqEnequeue: out-of-order valuator event; dropping.


The GPU is an Intel Q45/Q43 (using driver intel)
and the monitor is a DELL E178FP.


What else can I try?

Thanks

p.s: I you need my xorg.conf file or anything else please tell me!