I was upgrading Fedora11-->12. Booted from DVD, chose to install over the top of my OS (retaining settings), completed upgrade, rebooted. The splash screen appeared, then went black. I had a cursor in the upper left of the screen and could type but the system was not responsive. I had invented the typewriter! Yippee! Not. When I hit Ctrl-Alt-Del, I saw the usual shutdown sequence appearing on screen, of drivers unloading, etc.

So I decided that X-Windows was not working but the rest of the system was.

Here is where I made the Big Mistake: I put in the disk and chose Recovery. It told me I could fire up a shell and chroot to a certain partition, and I did. Now the reinstall forces me to blow away everything and start over (I haven't) and Knoppix will not mount the partition,and does not see my old data.

So, whatever chroot did, I need to undo. Then I need to fix X-windows.
I already had backed up the important stuff, so this is not the end of the world. But I would like to avoid a format reinstall.

Where to go from here?

Try a Rescue start again and try edit you're root in /etc/fstab by using (mount) instead of chroot

in boot try initdefault=4 ore initdefault=3 one of them is windowless and driv X whith the startx comand when its working you could drive the X-winlogin

and after that check for errors in you're boot directory /boot

And yes it sounds like you have a faulty X maybe an Xlock on 0:0
edit the /etc/initab to boot in consol mode and start youre system agin in blackmode :-) Consol