When i built my computer the first thing i did was install tf2 and i had this same problem, i was told it could be a problem with that part of my partition that the game was being installed so i uninstalled it, installed something else, then reinstalled it and it worked. idk if that will help you but you could shut the start up video off. maby, i doubt it, but maby that would fix it, you just go under your games tab on steam, right click on tf2, properties, then click launch settings, and type -novid "yes with the dash" that will get rid of the whole launch video, no idea if that will work but it could be worth a try