[SOLVED] Error - Black arrow on black screen

[elodman]

Greets Maestros!

Same issue here, after having used LL 1.8 and then 2.0 altogether for a few months (installed on HD, in a multi-boot Win 7 environment).  At the latest release LL 2.0 64-bit no problem was found until about 2 weeks ago I selected install updates. Since then black screen with a lonely arrow is the protagonist - but ONLY with root/admin, not with simple users (and all log ins require a password)!
And Power off button is the only escape route.
EDIT : WRONG, TERMINAL IS OK, SEE BOTTOM PART

Anyway could I use command SU or SUDO properly, or would in User Management granting SUDO rights to my simple user be functioning, no trouble would I have. (Though, spent 2 hours with trying and net reading, also in LL manual).

Some help would be fine.

(inxi -F is not installed, should anything be presented?)
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off: LL seems to be a very Great Distro after the many bloated and / or unstable, slow ones, used in last 4 years - thanx for it.

----EDIT: some success with terminal

Thanx for great info,

CTRL+ALT+F1 invoked terminal nicely in this no-GUI log-in case, where I could grant privileges to anyone

Code:

sudo visudo

reboot

Code:

shutdown -r now

log out

Code:

killall -u user

As couldn't summon X GUI with the other key-shortcut.