Error while i get root, it log me out

[humogt4]

Hello, I've a trouble with the Linux Mint 14 Cinnamon for 64 bits, when i open a folder as root to change the permissions of it, when i click the group combobox, the system log me out to the login screen, and when i try to log in again, it loops and take me again to the log in screen, so i have to restart the computer to log in successfully. The thing is that doesn't show anything to lookup to fix it.
I try to update - upgrade and reinstall all the operative system, and that doesnt solve the problem.

This problem doesn't be in the "GNOME Classic Session" in the 64 bits neither in all the 32 bit Linux Mint versions.

Thanks, i will wait for the solution or the response.