1 S 0 40 2 0 75 -5 - 0 - ? 00:00:04 kblockd/0
4 S 1000 14037 13959 0 80 0 - 1077 - ? 00:00:00 startkde
1 S 1000 14268 1 0 80 0 - 8102 - ? 00:00:00 kdeinit4
1 S 1000 14271 1 1 80 0 - 17239 - ? 00:00:02 kded4
1 S 1000 14412 1 0 80 0 - 6468 - ? 00:00:00 kdeinit
1 S 1000 14422 1 0 80 0 - 7278 - ? 00:00:00 kded

Still in KDE BTW

You are still running kde4, which is not being stopped by /etc/init.d/kdm stop because that seems to be for stopping kde3 only.
I do not know how to stop kde4 - maybe you could try searching on this.

But now we have a little more information, we can maybe help better.

Try this:
<CTRL><ALT><F1> to get a console login.
Login as yourself, then become root (as before)
Then:
[Edit]I meant "kd" in the above code post - Not a typo for "kde", as I'd like to catch something like kdm4 in that filter [/Edit]
Then start killing of kde processes, I'd start by killing startkde. That will probably kill KDE, but may not kill kde4's display manager which shows you the login screen. We can try though:
So, again: If any kde processes are still running, kill them.

Go back to your GUI screen - usually <CTRL><ALT><F7>
Looks dead yet?
If not, go back to your terminal screen with <CTRL><ALT><F1> and murder a few more kde processes.

When you are happy kde4 is truly dead, start a gnome session with
/etc/init.d/gdm start
Go back to your GUI screen - usually <CTRL><ALT><F7>
Before you do anything else, Select Gnome as your GUI. (Look very carefully at your login screen as to how to do this, there's usually a small button somewhere).
Then login as usual.

You should be back in gnome. Happy command lines and good luck.

If that fails, in a <CTRL><ALT><F1> terminal and as root do Then reboot. Hopefully you will find yourself at a terminal prompt. Go straight to "When you are happy kde4 is truly dead" (above) and start a gnome session.

I do wish people would realise that kde4 is still under heavy development, and you should perhaps resist the temptation to play with it unless you know what you are doing, or are prepared to suffer the consequences.

Anyway, let us know how you get on. I am very busy for the next few days, but will probably keep a watch on this thread if and when I am able.

root@ray-desktop:~# ps -Al | grep kd
1 S 0 40 2 0 75 -5 - 0 - ? 00:00:05 kblockd/0
4 S 1000 14037 13959 0 80 0 - 1077 - ? 00:00:00 startkde
1 S 1000 14268 1 0 80 0 - 8102 - ? 00:00:00 kdeinit4
1 S 1000 14271 1 0 80 0 - 17239 - ? 00:00:05 kded4
1 S 1000 14412 1 0 80 0 - 6468 - ? 00:00:00 kdeinit
1 S 1000 14422 1 0 80 0 - 9064 - ? 00:00:34 kded

o.k. I read up on the kill command but not sure which number above are the process number. I expect to use "kill 1077" or the like.

I tried apt-get remove kde4 for the fun of it and it said it was not installed.....

Thanks

Sorry I'm a bit new at this one.

OK.
Here's the first bit of the output of ps -Al on my PC:The fourth column is the PID number.
So in your listing to kill the startkde process you'd use
kill 14037
You'll need to get a new listing to check the current process number though.

Wow it gets more bizarre by the moment.

When I did kill 14037 the reaction was to return to my desktop as if I had done cntl>alt>f7.
I returned to console and it was still in root. Killing the rest of the PID's resulted in "no such process".

I think my machine is possessed.

I have had that happen, you did the right thing - just go back to your root terminal.
Presumably because they were children of 14037, and when the parent dies, so should the children (usually, there are of course, exceptions).

Any kde processes running now?
Login screen gone from GUI terminal?

If so, then try starting gdm as above.
You may be automatically switched to the gdm login screen, if not, search for it, it should be on <CTRL><ALT><F7>
When you login, make sure it is set for a gnome session (if you are offered the choice)

root@ray-desktop:~# ps -Al | grep kd
1 S 0 40 2 0 75 -5 - 0 - ? 00:00:08 kblockd/0
4 S 1000 20500 13959 0 80 0 - 1077 - ? 00:00:00 startkde
1 S 1000 20731 1 0 80 0 - 8102 - ? 00:00:00 kdeinit4
1 S 1000 20734 1 0 80 0 - 17232 - ? 00:00:03 kded4
1 S 1000 20873 1 0 80 0 - 6468 - ? 00:00:00 kdeinit
1 S 1000 20883 1 0 80 0 - 7839 - ? 00:00:23 kded

Looks pretty much the same.
tried to start gdm, then did a cntl>alt>backspace. logged in via the ubuntu login screen which went immediately to the KDE black screen of death. Can't seem to make it happen. I went into synaptic and checked for kde and the main programs are not installed but there a bunch of related KD items.

The Ubuntu login screen has no options for choosing a particular desktop. Odd

That's because you have meanwhile restarted X (which is still trying to run kde4, which is broken), when you did <CTRL><ALT><BS>:
In your post #18:
and in post #22:
You can see that the PID number has changed, so this is a new instance of the same process.

You don't say what happened when you had killed kde4, and restarted gdm

I am not sure our combined expertise is sufficient to sort this mess out.

Unless someone else comes up with an easier alternative, I suggest you backup your personal data and resort to a reinstall, but this time, please avoid the temptation to experiment with kde4.

When I restarted gdm it said it was already running. Indeed when I reboot the system I see that gnome is started during the boot process and no mention of kde. Maddening.