Plutonium

Well, the error occurs at the time of starting the "Plutonium" this does not even load, it just does the process and in seconds it throws the error "Plutonium has stopped" and going down to see the details of the problem, it says "CLR20r3" which seems be the problem and I have no idea what causes this, so they would help me a lot with this if they tell me a solution since I do not want to lose 2 days of downloading in the MW3