[client] Game not responding after a game is over

I'm having two problems with League right now.

1. After every game I click the button to continue to the post game screen. However, the client freezes and doesn't allow me to progress. I I bring up my task manager it says that league of legends isn't responding, so I have to manually end the program, which then brings me to the post game screen.

2. I am getting very low FPS for some reason. I played 5 games today. The first 3 were fine, I was playing at about 60-90 FPS as I usually do. Games 4 and 5 I experienced highs of 25-30 and lows of 9-15. I followed the guidelines riot posted regarding FPS issues, but I'm still having trouble. The last time this happened to me all i had to do was restore my graphics card settings to default. However, that isn't solving this current problem.