WPF crasing on Windows 7 when closing

I am having a weird issue. I am developing a WPF app, and I added a Setup Project in order to create an installer. I am developing on XP. If I install the app on my machine it works fine, but if I install it on a Win 7 Virtual Machine it crashes when closing. On Win 7, if I run the app as administrator it doesn't crash. When I go to 开发者_开发技巧Problem details it says: "Problem Event Name: CLR20r3"

Any idea? Thanks in advance.