Returning player: client crash durin champ select :( Please help me!

Hey! Since i startred playing League again (a couple of weeks) once every 2-3 games my client crashes during the champ selection. It appears to me a message saying to report this to riot and after 2 seconds the client reopens itself whithout showing anything. Rarely it loads fast enogh that i have time to lock a champion but 99% of the times I can't make it in time and i get a forced dodge... I don't know how many lp I lost for this reason and I already lost 3 promos. It's pretty anoying and I don't know what to do... I would be gratefull to anyone trying to help me out here, I'm kinda desperate :( I'm playing on windows 7 and I already checked my firewall. Thanks to everyone! :)