my game don't start when i load a character

Hello, when i launched the game all looks good and the game launch rapidly.
But when it comes to launch my charachter I have an infinite screen, I already uninstall and re-install the game but it didn't change anything. Sometimes when I have luck I can launch and play but after around 30 minutes it freeze and I have to close the game.
I don't know what to do and I don't find the packcheck I'm on steam and I have the game on my external hard drive.
Thanks for your time to help me, and sorry for the english it's not my first language.