Source SDK not loading Team Fortress 2 stuff

I've tried refreshing the content, and tried resetting game configuration. Then I uninstalled/reinstalled SDK and it worked the FIRST time I loaded SDK up. But when I close SDK and then open it again, it doesn't work for tf2 again. I recently finished my first "map" (the one in the video) but I ended up having to uninstall/reinstall SDK three times just to finish it. :( I'm thinking about trying is uninstalling/reinstalling TF2 and/or Steam, but I figured I would ask around first.



http://www.youtube.com/watch?v=LrBeNIeJH7M&hl=en

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