Well, i installed it, i patched it, and i start. I can play survival normally, but each and every time i do try to start a campaign, the loading will NEVER finish! No red bar appears, the loader is empty. Before patch, it would run normally. What do i do now? How can i play, WITH the new patch in? Please, help!

***SOLUTION***!
Turn off checkpoints, and it works as it should! Steam people had this very same problem, and were the first to post it into their forums! Too bad though, i really found checkpoints rather useful, damn...