Can't login as admin after upgrading from 11.04 to 11.10

Solution 1:

Removing ~/.Xauthority and restarting lightdm didn't work for me either, the file seems to be immediately recreated every time, however I did 2 things, possibly one of which solved my problem with logging in.

1. I had previously added some custom command to the file /etc/profile, which I removed.
2. There was another file ~/.xsession-errors which I removed as well.

After that and deleting ~/.Xauthority I was able to successfully log in, I don't know which of those things caused it though because I did them at the same time.
Hopefully this will be useful to you in solving your logging in problem. One other thing I did was to stop some services I had recently installed, but unless it took a long time to take effect that didn't seem to help either, might be worth a try though.