That's a new one on me. Do you have any extra peripherals currently connected to your pc, like a gamepad? Sometimes just having a device like that connected but not in use can cause odd control errors.
No, I don't have any sort of gamepads connected.
I found this listing the default controls: http://www.ldso.net/oldtronfaq/images/keycontrols.jpg
It says backspace does a 180 degree turn (turn around).
So, firstly, have you remapped the controls at all?
What language keyboard are you using? Could the region setting be picking up backspace (or your remapping) in error?
Then are you using any mods?
Yes, I have Backspace chosen for that as well but I never press it in the game. And I didn't change (remap) any controls.
I use Russian keyboard though... It has two layouts and I'm not sure if it does something.
And no, I don't use any mods.
One thing I've noticed using a USB mouse and USB keyboard, is that occasionally (for me) mouse movement and keyboard presses will somehow trigger an extra erroneous keypress.
Perhaps a Backspace keypress is being generated randomly because of something like that?