When I run your code as posted, but changing $test to be 1 I get two windows opened. One with the title "My title" and an OK button. The other is titled "Noname" and has a hello button. Clicking OK dismisses the "My title" window and leaves the "Noname" window. The "Noname" window is not active until the "My title" window is closed.

Could it be that your "My title" window is hidden behind another window and that is why you program seems to freeze?

My testing was with Windows XP