Bug#583774: Same problem here

[Roberto Fasciolo]

I've exactly the same issue (with the same errors in .xsession-errors) 
on a machine I've updated from lenny to squeeze. I'm not using an intel 
video adapter there but an nvidia.

I've noticed that besides gnome-panel not showing up at the same time 
two processes were consuming about 30% CPU each: udisks-daemon and 
dbus-daemon.

I found a temporary workaround that allows gnome to start up normally 
(but prevents gnome to detect when a disk in inserted in the system and 
also causes file explorer to crash when trying browsing a removable 
device): removing the org.freedesktop.UDisks.conf file from 
/etc/dbus-1/system.d.