Hi! It sounds like your 'crouch' button and the 'ragdoll' button might be getting mixed up. By default, 'Left CTRL' is the button to crouch/uncrouch (or crawl as you called it), and 'C' is the ragdoll button which will make your character fall over. Maybe your keybinds are messed up, or it's just a habit of pressing 'C' to crouch? I hope this helps!