I have no idea what you are talking about, nothing changed in the menus in 188.8.131.52 that I know of. Perhaps if you post a link to the site then someone could help.
Are you using a Superfish menu? It has that kind of effect by design but its not new.
Did you change from .NET 3.5 to .NET 4 as part of your upgrade? What version did you upgrade from? If so you might want to review the article The Trouble with ASP.NET Menu, you might also want to review the sticky thread of important skin changes.
Hope that helps,