Comment 15 for bug 955585

> Are you using a particular screensaver "hack"? Like a 3D one?

Nothing more than clicking on the "Lock Screen" Action Button. I didn't do any configuration of xscreensaver in either a gui control panel or in a config file somewhere.

> Or a random one, in which case you may try out cycling through the different screensavers until you see corruption. That would also be a driver issue, although in mesa/kernel, but it would help to pinpoint what exactly triggers it.

I will do some experiments.

I should note that, in the interim between 8 days ago and today when I've had a chance to look at this again, the problem has occurred after being logged in for that entire time without locking the screen.