[Client] Client shuts down during game. (And sometimes crashes when not)

Any time I enter a game or spectate, after about 15min or so, the client in the background goes poof, the process just shuts down. Then when the game ends i have to relaunch and login again. Also, sometimes when not in game i get (much too frequently) that LoL Client has encountered an error and must be shut down (or some such). Running windows 7, just reinstalled LoL entirely to no avail. Also getting the constant PVP.net disconnects while in client. Nothing i've been able to dig up has helped in the least. Any suggestions?