Everything was working great and my Visual Studio 2010 Beta 2 stopped starting.  I tried to reinstall VS2010B2 and that did not fix the problem.  I just got this stupid error:

The application cannot start.

Some google searches turned up Weston Hutchins blog on the issue.  I tried several of the steps and noted this difference on my system.

He says that your personal settings files are stored here:

%USERPROFILE%\Documents\Visual Studio 2010\Settings

I actually found them in:

%USERPROFILE%\Documents\Visual Studio 10\Settings

Weird.  So I blew them away and restarted.  Got the same error.  So this tells me there is more to it than just the settings files.  There must be a settings file elsewhere that is the culprit.  So I moved on to the next step that actually worked for me.

Load the Visual Studio 2010 Beta 2 command prompt and type: devenv /resetuserdata

Viola!  This worked and I got the following screen:

After this I got the screen asking you how you want the development environment to be configured and it sets up the IDE in the default manner.  But everything is working great now!