Using v.1.9.40-compiz, I have a hard lock-up that can occur after waking from suspending the computer. For instance, just now I had to hard-reset the machine when I started Picasa while using Opera, Iceweasel, Thunderbird, and a video in VLC going on at once.
This sort of thing has happened before with different apps open, and not just when trying to use Picasa. But it always happens after being suspended.
Also, the guide says to use Control+Alt+ End to reload, but this does not work when this happens. It is a very hard lock-up.
My advice is to always turn the thing off. Please post if you have any insight into this.