I was using Visual Studio 2008 in Virtual PC when I accidentally pressed a Help button. It was a virtual machine so no one used the Document Explorer before. Visual Studio user interface became unresponsive, Help system started processing help files. I got tired of it after a few minutes.
Workaround for the problem:
- Kill Visual Studio 2008 (from Task Manager)
- Set Document Explorer thread priority to Below Normal
- Restart Visual Studio 2008
So help system will be initialized next time and you can continue working on your project.