I just installed Ubuntu 15.10 on my convertible laptop(hp 2760p) It has a button to turn the screen 90 degrees. I loved that it worked properly, but there is always a little BUT.
I used this button, and now every time I log in, it starts the system turned 90 degrees. It's not a huge problem, but it's annoying When I was shutting it down the screen was in a normal position.
P.S.: I know I could run a script that would turn it back every time I log in, but I also want to know why is this happening