VS Auto Get Latest
Did you know Visual Studio will download any changes made by another person when you check out? When you go to make a change to the file, or select the check out option, Visual Studio gets the latest file for you and prompts you that other changes were made before you (I don't have the exact prompt text right now).
However, this can produce an error when it comes to ASP.NET pages. Let me explain. Suppose you go to the code file of a page. You hit the spacebar, and this checks out the file, while prompting you that a change was made and you do not have the latest version. VS downloads this version of the code file for you. Note what I said; it downloads the code file, and the code file only.
I was getting an error because a control wasn't being downloaded, because VS didn't get the latest ASPX file, and thus my code was causing an error. This can be problematic in the long run, if you do not automatically get the latest files manually.