Kiosk: some keys start Windows functions

When I am into Kiosk (6.3) sometimes I can’t write as pressing certain keys starts certain Windows functions. The letter “e” starts Explorer, letter “L” starts the window that asks the Windows password, letter “r” starts the Run function.
Is it a bug of Kiosk?

It sounds like may be the Windows button of your keyboard gets stuck sometimes. It does not happen in Kiosk on my Win 8 x64.