I spent a few hours installing Linux Mint 21.3 on a PC yesterday. I added a few pieces of software, set up my main screen and panel with the apps I would use most often, and tested it. Everything worked fine.

So, I shut down the PC (using the power off option from the menu) and moved it to the room where I intend to use it.

When I finished connecting the monitor, keyboard, etc., in the new location, I booted up the PC.

It went to a screen for initial setup of Linux. I can't get to my original install. It's like, somehow, the machine erased all my configuration settings, and reset it to the point where I choose my language, location, keyboard, and so forth.

I have installed Linux Mint before on other machines and they worked fine, but this is a new one for me.

Sure, I can go through the setup and configuration again, but there is no guarantee that this won't randomly happen again in the future, wiping out all my configuration settings and files.

Any ideas??? I'm at a loss.

I have never encountered anything remotely like this with any Linux distro.

Just to rule it out, I have to ask (knowing the answer will be no), did you perhaps have installation media (USB or optical disk) connected to machine when you turned it on?

Thanks for asking, but nope, no install media was in the machine. No CD, no USB, nada.

It's truly bizarre, and like you, I have never encountered nor heard of anything like this happening before.

Welcome to LinuxQuestions.

Are you actually looking at the Mint welcome screen? If so just uncheck the show this dialog at startup checkbox.

Are you booting back into the live install media? Did you unplug the flash drive used to install Mint?

Nope, not the main Linux screen. I get the little spinning Mint beachball, and it gives me two choices to boot Linux. Either one I select, it brings me to the initial setup screen where the language, etc., are selected.

And no, as I replied to someone earlier, no install media is in the computer. I have booted and rebooted it in the ORIGINAL room where I installed it (my home office) and when I moved it maybe 25 feet to another room, all my configurations went away.

Very strange. Are the two choices the Grub boot menu?
Can you boot the install media and access the drive?
Try running fsck on the drive's partitions.

It always boots fine in one room, but never in the other room?
Network issue? Odd thought: is it booting the net device? (vs disk)
Boot in 'rescue' mode (or init=/bin/sh)

If you do boot the install media and run fsck as suggested, you could also post the output of sudo fdisk -l which might give some hints. If you installed using a USB, what software did you use to write the iso to the disk? Were any errors reported during the install, warning messages?

Thanks for everyone's input.

It continues to be a weird tale, but here is what happened so far.

Again, for those who asked, I was NOT booting into install media nor the net device. As for the location being a bad network location, I took a windows laptop into the same room... put it beside the machine, and it connected to the Internet just fine, both via WiFi and via the same ethernet cable I used to try to connect the Linux machine.

I gave up on it for the moment, but returned later that night after coming here. When I booted the Linux machine it came up cleanly to the initial Linux Mint login screen. I was able to log in to Mint and see all the apps... but I could not connect to the Internet. I tried various things, with no success. After an hour or so, I was frustrated and had other things to do, so I shut down the Linux machine and went away.

Next day: I booted the Linux PC again. When I logged in, I opened Firefox and lo and behold... there was the Internet. Facebook, Amazon, Google, the whole shooting match.

In between all these things, NOTHING HAD CHANGED in my configuration, my network setup, or anything else that I know of.

It is still working just fine, still connecting to the Internet, to my network printer, etc., etc.

I'm glad it is all working now, but this is one of the more bizarre things I have experienced with PCs.

Again, thanks for everyone's input. As long as the machine continues to work, I'll monitor it and use it. If it refuses to boot fully again, or if the Internet disappears (with WiFi or Ethernet), I will probably return here for help again... that is, if I don't decide to put a few ounces of thermite in the PC case and dance naked around it while it melts to a puddle of goo.