Help!i can't play!

HELP!I am trying to start the game,but i can't,it keep show this 
I didn't open AA.exe but it always show up that!HELP!!!!!!!!!!!!!!!!!

I didn't open AA.exe but it always show up that!HELP!!!!!!!!!!!!!!!!!
Comments
Does a system restart fix the issue?
You cannot start another mission while one is already running) still there.
Looks like it.
http://forum.americasarmy.com/discussion/5808/aapgmod-v1-0/p1
Try deleting the appcache Steam folder, then restart Steam