Microsoft Program Manager interview questions

I was first asked some basic admin questions, one to prepare is: which level do you want to work on - UX, Application layer, OS or hardware (from high to low level) ? Then a question about threads & processes (detailed below) then a simple question asking me to write code to reverse the words of a sentence. So "the car is blue" -> "blue is car the". I explained that I was going to parse string into 4 word strings, push them onto a stack and pop them out in the right order, adding spaces where necessary. The whole thing lasted about 25mins, and I got through to the next round.