Yikes! I could have written the exact same thing! I had a meeting with my boss to negotiate a higher salary. Instead I got ambushed by HR and my boss's boss. They made mountains out of molehills and put me on probation. I had no idea that I was doing so badly. I'm really flummoxed. But you're absolutely right. HR is not your friend. At best they'll pretend they care and then forget about you. But usually they'll find a way to turn your words against you.