I froze some pastry with whipped cream on the other day (by mistake, I placed it on my balcony and expected it to be a few degrees above zero, but it wasn't). When I unfroze it again I was expecting the whipped cream to become soft again (or, I was actually expecting it to "collapse", that is lose all the air whipped into it) but instead, even when it was at room temperature, the whipped creamed remained basically as firm as it was when it was -10°C. Leaving it for a few hours didn't change that.
Milk, "unwhipped" whipped cream, butter and so on all can be frozen and then thawed and the result is more or less its original texture and consistency (just a quick shake and your fine). Why does whipped cream behave so differently?
Edit: I can add that I have googled this and find a lot of articles that confirm freezing whipped cream is a bad idea but no one explains why.