Crashes

Ok so I've recently gotten into league and I've encountered the same issue about three or four times now. When we enter the loading screen to wait for every one to load in, the game crashes. The crash isn't a big deal, but what happens is the crash report appears under the game and the game refuses to close. So there i am with a blank screen. I can't alt + F4, Can't alt + Tab, and using my other monitor to close the game also fails to work. My friend has also had this issue, but i was wondering if anyone else is experiencing this. Because it forces me to restart my computer and by then i've basically screwed over my whole team. Also, if anyone has a solution that would be great.