I've been looking for any case similar to mine and still haven't found one.
The story: I'm using arch linux, updated just last week, and it was working fine. I never configured auto-login, so I have to input my username and password everytime I boot. Today I decided to reboot, but when I tried to input my username I noticed a special character ^@ being added at regular intervals (aprox. once per second). I tried logging in while ignoring the character, and failed repeatedly, which led me to believe that the character was actually being added to my input, as if a key was stuck. I also tried changing to other tty but the problem persisted.
I didn't think it was a key stuck because to write that character I would need at least two keystrokes. I also booted using a bootable ubs stick and the problem did not appear, which proves it's not just a hardware problem.
Using the usb stick OS (and chroot), I updated with pacman -Syu, but it had no effect on the problem (note: I seem to have some messy dependencies with pandoc and haskel but I don't think they could have anything to do with this issue).
I turned it on and off a few times and noticed that the character started appearing in the boot sequence, right after the message of started udev Kernel Device Manager.
I never had anything like this happen to me, and it's very frustrating how it makes it completely impossible to even log in, so I can only work using the usb stick. I don't know how to even begin troubleshooting this, so any help is appreciated.
