Ok, I'm getting this issue, a lot of my friends say they get it too, but not as near as bad as me.
My TF2 closes with no error on ANY server at ANY time when I first join a server and go to the class selection screen. It just freezes and closes with no error. No explaination. I have tried reinstalling, deleting the TF2 folder, restarting the computer, doing -windowed -noborder, defragging, verifying, doing a map/mod backup, etc. Please don't give me stupid answers that you know won't work. They're a waste of time and won't help anything.