[Storm of When]

I just bought and installed the Wick Dundas campaign for IL2 Cliffs of Dover, however if I press esc during a mission the game exits to desktop with no warning but continues running in the background, to shut the game down I have to end process the launcher.exe. I`m running the latest Steam patch, with Win7 64, a 7870 with 12.9 drivers, 8gb Ram and a Phenom II Be955 at 3.7ghz. When I installed the add on, I installed the high spec version. Can you help me to stop this happening please