To All Who's League Won't Open

Add League to your antivirus list of exceptions, you will have to also restore what it blocked as well, if you have Avast! just go to the virus chest, right click on the file it blocked, and select restore and add to list of exclusions and you are done.

I don't know why but league just doesn't seem to work well with Avast!, i swear i have to do this nearly every damn patch, but it works at least until the next patch, don't bother with the whole uninstall crap, that is a waste of time and not needed nor will it fix the problem.