Hello everybody I am newbie.
Well the thing is that i just upgraded from hardy heron to intrepid (from kde3 to kde4)and while the instalation process the "cleaning software" never ended so i just clicked on restar pc. Then the message asking if I would like to remove old sw appeared but it was already to late. (do not know if this is a problem)

Well I logged in I was exploring the desktop and the menu, there was a litlle flashing on desktop and here is the main problem I was train to configure all the effects too see my pc was going to suport them (I got a 1.20 gb CPU, 608 RAM and 32MB video integred ,a friend told that he could apply all the visual effects on his similar characteristics laptop) I checked the box about something like embeded alt+tab feature and since them all is black desktop apps ,etc.

I tried rebooting the system would work but nothing happend.

when pressing alt+tab i can see the apps running but when i select them i do not see anything even on the konsole, thankfully i did alt+F2 , konsole, sudo shutdown now, then typed my pass. When it turns off my desktop appear but it is already to late.

so, what can i do? should i download kubuntu intrepid and make a new installation? i do not want to lose my bookmarks and that kind of stuff, please send some links to documentation (i still will be researching but help me in the process). Or should I look in other site? Please send me some feedback Thanks.

When your computer starts up, does the graphical login prompt come up fine? if it does then simply switch to the session type 'failsafe' then login as normal. This should bring you to a terminal.

You should be able to use graphical text editors at this prompt, but I would avoid it. Try vi, press insert once to enter editing mode, then when you have finished, hit Ctrl + C, then type :wq to write your changes and exit. if you do not want to save then type :q! instead

Since it is the KWin desktop effects causing this, edit the file ~/.kde/share/config/kwinrc, looking for the section [Compositing]. make sure enabled=false. Once you have done that, return to the console, logout, set your session back to what ever it was before, and you should be able to login back to your KDE 4 desktop without problems.

You may also want to try using "nano" instead of "vi", as it is much easier to use and understand for a beginner than vi.

I tried but I can't. I mean when switch to session Failsafe it keeps loading the (i do not remenber) ¿K Manager? so I have to press ctrl+alt+supr then it tells me the process k .. (i am sorry i do not remember)

Can I do it by starting the kubuntu8.10.XYZ (safe mode) in the masterbootloader, cause i tried it before and a Menu comes up and I could do many things like a checkdisk , a paquet check and I remember a saw a login as root in the console mode or something like that.

THANKS FOR THE REPLY, i am sorry if i am being annoying.

After you start your computer and KDM (the login window) loads, use Ctrl+Alt+F1. This will take you to a text login. Type your username and password, and then the edit the file as described above.

Once you have finished, you can go back to your login window. Type "exit" to logout, and then use Ctrl+Alt+F7 (I think...) to get back.

So it worked perfectly and it took me like 2min. I must thank you both for the help, thank you very much.
I still have the flashing lines in the screen specially when I type .