What is your "HR is there to protect the company" story?

Worked with a women from another company co-managing a trail running event. We worked catering and bar, she worked 'customer relations'. She drank on the job and would boss my staff around with nitpicking like "pick up that bottle cap that guy at that far-away table dropped on the ground" and having photographers come behind the bar to take some "action shots" during the lunch rush. By the end I had spoken to my boss about her several times and he told me to "just play nice". On the final day the main organizer came by and spoke to all of us and asked how it went and if we all got along. My boss gave me a subtle jab in the ribs and I said "yeah it was fine". She also had nothing to say. The next morning I get a phone call from HR telling me that several accusations have been levied against me from you-know-who, ranging from drinking on the job (ironic) to abusing staff and all the way down to sexual harrassment (that was low). Mind you this is now 9am on a sunday. Go in to the office for a sit down with my boss and HR. Oh and she wasn't there because she DIDN'T WORK FOR US. After half an hour of reading the essay/ email she sent at 12pm, the question finally comes. "what do you have to say for yourself?" I look at my boss who was there and whom I had spoken to several times over the course af the event, and he... looks away. So I call the other staff who worked and ask them what they saw and if there is any validity to the accusations - an all round resounding NO. HR thanks me for coming in and tells me they will look into it. A few weeks later (past payday) I ask why I haven't been paid. The reply... "oh do you still work for us?"