I've pclos 2011.6 LXDE Mini, running alongside pclos 2011.6 MiniMe. I choose which Distro, from Session Link.
I was logged in to LXDE mini.
Had a few flickers on my old CRT Monitor recently, so I felt it may be wise to look at the Configure Graphics Card section of PCLinuxOS Control Centre.
I guess it's probably useless to change to the exact model of my monitor, as against Plug 'nPlay, but I was looking to fix a small problem, so as the monitor was listed, I selected it. You look for those type of things I suppose, when troubleshooting, and certainly wouldn't think it to be a problem ?
Also checked the box; "Use EXA instead XAA" (Better performance ...)
See Pic
That all seemed quite straight forward, not dangerous.
I was asked to Reboot, after the changes. Did so, but trouble ensued !
Computer turned off !!!
Restart: GRUB found, and continued but boot process fell into a loop.
Some text = Green [o.k.](Good), then a flicker, and repeated, over, and over.(Bad)
I attempted to turn the machine off manually, with powerbutton (usually 5 secs push),however instead presented with a command prompt; at which I typed 'poweroff '. Once totally OFF I pulled the power lead for 5 mins, before rebooting. If it works for NASA ... In reality unloading charge from IC components is why this works, on occassion.
I'm no wizz at all with Commandline in Linux, which I must remedy!
Restarted Comp, the same loop happened, flicker, some checks, all green o.k.'s, ...I turned off the Computer, via Command prompt, "poweroff", Rebooted, started selectively, and carefully pushing some Keys, guessing.
Again, rebooted.This time I was presented with Commanline prompt -Login, logged in, somehow guessed a command which brought up a little System Menu.
I chose Display, shocked to see options as in Pic above. I unchecked "Use EXA instead XAA" (Better performance ...)" , was asked to reboot, ... I was pretty panicky but at command prompt after being told to "reboot" I did.
Thank the Computer God's it booted to my normal Login screen, I selected "Session Link" >
KDE as by Default would've logged into LXDE, which I wasn't confident. It logged me in o.k. !!!
Just acted instinctively through the whole Boot, Loop - fiasco.
I unconsciously have remembered commands to a degree, or they are semantically logical, as i hit a few correctly to get me into that PCC Menu, very lucky indeed !
Only real hard Info i have is the unchecking of "Use EXA instead XAA" after crazy loop during Boot, and luckily found a very simple 'Menu' to undo that checked box!
I was using LXDE when changing Video card settings.
I'm posting this wondering why changing THAT Video Card Settings seemingly caused this instability to happen ? 
