This is a bug that only happens on my desktop system.

System Background: Triple boot, Kali 2.0, Kubuntu 15.04, Win 10. 3 Int-HDDs, Grub loader on SDA which all primary OS partitions reside on. SDB & SDC contain no primary system or boot files. Radeon 8500 PCI-E card running 3 monitors, aside from that everything should be considered generic 64-bit arch hardware with 8GB of RAM. None of the OSs are virtual.

So with that out of the way here is my issue. And I say issue because it appears to only happen on this system and I have multiple Kali sys, but as the system is loading sometimes, but not always, my screens will show the display contents of a previous session that I was running. For instance let's say last time or maybe not even last time, but a time before, you had a browser open looking at your email, Kali will display the screens as if that session was still live prior to the displays going to the login screen.

This particular system's HDD has been reformatted with different OSs and partition tables more times than I can count and I did notice this bug on first initial boot after a complete reformat and clean install of kali 2.0. At the time I kind of wrote it off as if maybe some data streams were being read off the hdd and Kali just didn't know how to interpret them and what not (The previous installed OS had full-drive encryption) and said if it happens again I'll just do a multi-pass wipe and clear the hdd of any possible remnants of the prior OS, but it didn't happen again for a while. A few months later I see the bug happen every now and then always with different content pertaining to a recent session. So I believe this to be something intermittent, it does not happen on every boot. The display of the previous session is not live in any way as the mouse and keyboard handlers are not active at that point, however it is a security concern as it displays the contents of the previous sessions display clear as day. Running diagnostics and performance benchmarks show nothing out of the ordinary and are within normal ranges for this system.

This only happens on boots into Kali. Kubuntu and Win10 never show the bug. Some of my initial thoughts:

1. Graphics card RAM not flushing prev. session contents: The majority of the time the bug appears, it's been on a reboot and/or switch from other OS, but I know that it has happened at least once off a cold boot.
2. Prev. sleep/hibernation or improper shutdown session dump is being accessed by one of the services at startup. This particular system never enters sleep or hibernation and the only improper shutdowns occur due to loss of power or the occasional service that just won't stop after the shutdown sequence begins and I just have to hit the power to turn the machine off. Both of these instances is not even remotely often.
3. X11 service pulling prev. session data from the config files or something therein: I actually think this is where the bug is, but looking at the logs everything seems normal. Which I think makes sense because as far as the system is concerned no REAL or fatal error occurs. But seeing how this is a display (data) issue it makes sense for this to be the source.
4. Driver: I run the default ATI/Radeon driver, I'm well aware of the problems with the "fglrx" driver in Gnome3 systems which even though there are a couple known workarounds, I still run the generic provided by the the distro.
5. 3rd party Display or Video software: Aside from player, no additional video or display software installed.
6. Other OS conflict, this bug was first noticed prior to the other 2 OSs being installed.

Aside from all that I'm kinda a lost and hoping somebody can point me in the right direction. Maybe someone with a good amount of fine-detail knowledge of X11? But I'm open to any and all suggestions before finding myself with the only last remaining option I have left, which is to blow the whole system away and see if the problem is still present.

Thanks in advance for any input anybody can provide.