VS 2010 Beta 2: How to fix "Object reference not set to an instance of an object" when trying to build

Question

We've seen several reports from customers who, when attempting to build, are presented with the error message "Object reference not set to an instance of an object."  This is most likely due to a Beta 2 bug where undocking and redocking tool windows sometimes causes them to disappear.  For this particular case, if the Output window is the tool window that cannot be displayed, you'll get this error when trying to build certain project types.

To fix this error:

1. Open up a Windows Run Prompt (Windows Key + R)
2. Type "devenv /resetuserdata"

NOTE: This will reset your settings so if you want to persist your current settings file, make sure you create a backup in Tools->Import and Export Settings...

Thanks,
Weston Hutchins
Program Manager - Visual Studio Shell Team

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