The problem was first reported in this thread but I will re-iterate:
In order to switch keyboard languages with the assigned windows hotkey (which is ALT+SHIFT for me) you must hold down the alt key and press the shift twice in quick succession and it works - always. I'm glad I found a way to make it work consistently but not so happy that Notes will work differently than every other Windows application the users are familiar with.
I am using French Canadian and US English keyboards. 50% of my e-mails are in French and 50% in English.
Feedback number AQUI745KSJ created by Asad Quraishi on 06/13/2007