I updated the game to the newest official patch, and when I tried out a weapon in the virtual arsenal, I noticed that I could not fire my weapon at all.. But sometimes after I clicked "change firemode" and then hit the fire button it would instantly change the firemode back to semi. So I figured out that the latest update does not allow you (me in this case) to have a key binding doing two things.

I am using a customized arma 2 controls preset, and when I launched the game if asked me if it should change left shift to hold breath.. I clicked "No."
I tested if this bug was related to scroll menu select key, and it is. If I remove the select key from being primary mouse button, I can then shoot my gun. So for now I am forced to use middle mouse button to use selected in the scroll menu.. It's a bit annoying but I guess I can live with it.. I am just fearing this update has also changed other control restrictions, whitch I only notice when needing it to work properly.