I had just moved to United States with my wife and my 7-year old son. Since this was the second time I had moved from one country to another, I expected to be able to handle it reasonably well. Instead, I got seriously depressed by the absence of my friends and the cultural paradigm shift (i.e. the Seattle Freeze). I also had to deal with my family's emotional fallout -- both my wife and my kid got depressed and I was trying to help them as much as I could. On top of it all, I got an abscess and had to go to ER. As a result, my productivity dropped to zero.
The problem wasn't the productivity itself, but that I had mismanaged the situation. Instead of trying to talk these things over with my manager, I kept pushing myself, promising to deliver and failing to do so. It came to a point where my manager scheduled a 1-on-1 with me and told me he had no option but to put me on a PIP. He said he was extremely perplexed, because he had formed a completely different image of me during interviews and thought I would perform much better. During the 1-on-1, he kept prodding me to explain what was going on, until I broke down and explained the situation. He asked me why I hadn't told him any of that before. I explained that I had thought the American corporate culture was that you're expected to leave your baggage at the door and that nobody else should pick up your slack -- you're here to work, not to be babysat. He was appalled by the idea and explained that I should've talked to him and we could've organized things better. He reiterated that, because my lack of performance had percolated up the food chain, he had no option but to place me on a PIP; it wasn't merely up to him anymore. He explained that a PIP was a chance to prove that I really was capable of fitting my role and that if I met the PIP goals I would be in the clear, not just with his team and at that moment, but in the future too - managers aren't allowed to hold your PIP against you.
We then sat down and worked out a PIP. During the following 6 (or was it 8?) weeks, I met all the goals and that was that. After 2 years of working on that team, a much more exciting opportunity for internal transfer opened up, I applied for it and it worked out great. Nobody even mentioned my PIP.
In my opinion, that's how a PIP is supposed to work. For anyone interested, the company in question was Amazon. There are lots of things one might criticize about Amazon, but this is one thing they did absolutely right.