Breaking clips, destroying whole project

I bought after effects few weeks ago and everything was fine. Now when I want to make a project every video I will add is breaking, green lights are appearing and everything's dystroyed. I can't see normally video because everything you can imagine is appearing on. I don't know how to fix this I tried to clean my storage and it didn't work. It's really important to me because I can't do any project now. Help me.