Any message printed in the screen? How does the loop look like, what are you getting (e.g., are you continously going back to the login screen)?
exactly, yes
I can retrieve command prompt If I choose recovery mode in grub menu at booting timeYou can boot in recovery mode and work from there, at least you will able to look at the logs (the interesting one should be the "~/.xsession- errors" file).But if i choose recovering regime of downloading there are no problem.I don't understand what you mean here :-?
I want erase kde but I can not because after this erasing the loop mentioned above occurs. Which setting I should change and where for normal gnome starting?
Reading xsession logs does not give me any idea about it.I think the problem is not in X-session but in gdm3, because gdm3 to kdm changing resolves problem with booting gnome3.
Any idea?