some ways to solve/help you out of ur trouble
I am still using Finject (faithinject) so its not injector.
when you close combat arms and press to much inject it will inject when it isnt started, i know.
btw if ur working on windows vista/7 u need to start it as an admin.
you also have to check when your on 64 bit system, Do you have the good injector?
otherwise look for another injector