Re: Game \'locks\' at \'Loading\' screen
No, actually unpacking the files from the GCF would cause the game to run slower. I don't *think* the files are compressed in the gcf per se, just contained...but I could be wrong there. Anyway, the bonus to having a lot of files contained in one bigger file is that you are actually cutting down load times created by opening and closing lots of files.
Anyway, what I was going to suggest is to verify your game cache integrity. You can do this by right-clicking the game in Steam, going to properties, clicking "local files" tab, and pressing "verify integrity of game cache." See if this fixes your issue.