mmoy firefox
I haven't done a rigorous analysis or set of tests, so I don't know what was going on under the covers.
I probably should have written that at the desktop level, it hangs. (but it was fun to poke at MS :)
The one time that I looked at the task manager, I saw that firefox was active, that the memory usage was growing and the number of page faults rose.
Nothing actually happened at the desktop level, however and I did have to shut down firefox with the task manager.