Is controlsend bugged?

Hi, I'm having problem with script in au3. For example when I run code like this below:

ControlSend("Notepad", "", "", "D")

it is working, but after 3 minutes it is sending "D" everywhere, to Firefox, wordpad etc. When i press "Shift/ctrl/alt" my keyboard is getting bug, and it doing some crazy things.

Thanks for help, sorry for my english.

Walrus.