I have the same problem with my login after I installed a number of stuff. But all other logins and root are all well. I tried renaming the .kde-folder, but it didn't work. But after I tried it, I found out that also the other desktops didn't work. I wrote my password, pressed enter and ended up at the login-screen again quite quickly. BTW, the fail-safe desktop worked.
I haven't tried the tip with .xintric yet, though, but I'll do it today. If that doesn't work, I think the easiest thing is to delete the user.