I have been having a problem editing HTML files with Visual Studio. This happened on my work and home laptops. I knew this must be a configuration issue since I just reinstalled Visual Studio 2010 Professional on my home machine. Every time I open an HTML file with Visual Studio, I get a blank page. What the heck? Opening the same file renamed to a ".txt" file works fine.
I tried setting some options. That was no help. Then I started playing with the File Open dialog. With the HTML file selected, I clicked the drop down box on the Open button. Then I chose the "Open with..." submenu. The HTML Editor was the default program used to open HTML files. That must have been the fail. As soon as I selected and made the Source Code Editor the default program for HTML files, I can now see my code.
The strange thing was that when I googled for solutions to this problem, I got no help. Sometimes you got to get in there yourself and do some hacking to get your tools to work correctly. I still think Visual Studio should be able to edit HTML text straight out of the box without any such hacking.