Odd login fail problem

I have set up an Asus EEEpc 901 netbook with a broken screen as a retro game
emulator station connected to a 1366x768 led monitor hooked up via VGA out.I
have installed Trisquel 5.5, but previously (before being turned into a Sugar
machine for some nephews) to that it ran whatever the latest Trisquel was in
2011 (4.x I think). It ran flawlessly then.

The problem is that now after 2 times of successfully logging in, I cannot do
so anymore. I enter the correct password, and the screen looks like it is
about to do something, but then I am returned to the login screen again. This
continues indefinitely and I do not get an "authentication failure" message
so I know the password is correct. I cannot determine what is causing this.
My only guess is maybe something to do with the monitor being connected?

Have you tried to log in a terminal (that you can obtain by typing Ctrl+Alt+F1)? If it works, what does 'startx' tell?

Have you tried to log in a terminal (that you can obtain by typing
Ctrl+Alt+F1)? If it works, what does 'startx' tell?

startx gives me:
Fatal server error:
Server is already active for display 0
If this server is no longer running, remove /tmp/.XO-lock
and start again
Please consult the X.Org Foundation support at http:wiki.x.org for help.

ddXSigGiveUp: Closing log
Invalid MIT-MAGIC-COOKIE-1 keyinit: giving up
xinint: unable to connect to X server: Connection refused
xinit: server error

If I hit Ctrl+Alt+F7 after logging into the CtrlAltF1 terminal, it just shows the login screen with a green check mark in a circle next to my username saying that I am already logged in, but it still has a password prompt. Entering the password will produce the same loop of it looking like it is about to log in, but not.

When I run sudo gdm restart from the F1 terminal, I get:

**(gdm-binary:1754): WARNING **: Failed to acquire org.gnome.DisplayManager
**(gdm-binary:1754): WARNING **: Could not acquire name; bailing out

Creating another user just gives the same problem. When I try to startx, it does say this now however:
Server is already active for display 0
If this server is no longer running, remove /tmp/.XO-lock and start again

I was able to ls /tmp/.XO-lock, but typing rm /tmp/.XO-lock did not work. How do I remove that file, if it is a file?

Yes, I did try as root and I get "no such file or directory". I get the same when trying to ls it. When I type /tmp/ and then TAB to complete, it shows up as .XO-lock, but ls and rm claim it doesn't exist. The error message tells me to remove it, so I think it is really there, but I cannot delete it, even as root.

I discovered that I had to type .X0 (numeral zero) in the filename. I was then able to remove it as root. However, it did nothing for the problem.

I have settled on setting up an 8GB USB drive as a Trisquel Mini Live USB with 4GB persistent storage. As it boots fresh each time, I have so far had no configuration issues with getting my monitor to work each time. I do not see any progress with the X problem on my installation anytime soon and may install another distro (one of the few fully Free ones) on the SSD later. The Live USB runs acceptably well for now.