[cesarb]

I've seen worse.

An old Dell laptop, which originally came with Windows, repurposed as a Linux laptop. It had been used exclusively as a Linux laptop (the Windows partitions had been overwritten by the Linux install) for several months if not years, when one day, its lock screen displayed a Windows desktop (I don't recall if the laptop had just returned from suspend or not). Moving the mouse dispelled the "ghost" screen and showed the normal lock screen.

The only explanation I could come up with for that was that, somehow, that particular screen had survived intact in a corner of the video RAM, for months, until a bug in the Linux video driver made it appear.

Makes one wonder how long can information survive in a laptop's video RAM. The laptop had never completely lost power (it has a battery, after all), but it had been powered off daily; it wasn't left on suspend all the time.

[brokencog]

Just to clarify ... the laptop you describe was powered off daily? Even Once? Powered off?

Then what you saw was NOT a VRAM artifact. Aside from OP clearly stating it is a re-boot issue, powering off the laptop would have removed power to the video RAM chips -- thus they would have lost their stored data.

What is likely you saw was a screen saver program displaying a random image which it found on the laptop hard drive. How this came to be found (assuming it is what you saw, just to give you the benefit of the doubt) would be very hard to guess without the laptop and it's configuration.

[cesarb]

That was a long time ago, so my memory is a bit hazy on the details. If I recall it correctly, it was the laptop I was using at the time, and I almost always powered it off when leaving work. I still have another laptop of the same set at work, so I could look up the exact model tomorrow if you want (it's an old Dell Latitude IIRC).

But I can clearly recall that I thought at the time precisely that: "how is that even possible, powering off the laptop should have cleared the video memory, and this laptop didn't have a Windows install for years!" Yet, there it was, a Windows desktop with one window (or dialog, can't recall precisely) open. (I don't recall how I knew it was from its old Windows install; it might have been showing some work-related information.)

It wasn't the screen saver; IIRC, I used the "blank screen" screensaver (or some other equally simple screensaver), not a "slideshow" or "random" screensaver.

Yeah, it's hard to believe. I myself would have found it hard to believe if I hadn't seen it. I even took a photo, but it was several mobile phones ago, so I'd have to search through my old backups to see if I can find it.

The only explanation I could come up with was that the video memory on that laptop for some reason retained its contents as long as the laptop battery wasn't removed (while the laptop had been powered off many times, its battery had not been removed), and the Windows driver used the video memory in a different way than the Linux driver, so that desktop snapshot never got overwritten. Then one day a glitch made the "read the screen contents from here" pointer point to it, and so it showed in the screen. It's ridiculously unlikely, but I couldn't come up with a better explanation; it's even more bizarre in that the "ghost" image was perfect, with no visual glitches.

[agumonkey]

These stories, and the hdd full fledge arm controllers[1] makes me thing we need to correctly map and manage every bit of memory and processing unit in our machines.

[1]http://hackaday.com/2013/08/02/sprite_tm-ohm2013-talk-hackin...