Visual Studio 2010: Object Reference Not Set to an Instance of Object

Hi Experts,
I am running Windows 7 Pro with 4GB RAM. I used my Admin account to install all my software applications on this machine.
I am not able to succeed in getting my Microsoft Visual Studio 2010 work with Windows Phone developer tools. I am getting an error message. I have tried to repair both MS VS and Windows Phone developer tools, but in vain.
Any ideas?
Microsoft Visual Studio 2010 Express for Windows Phone
Object reference not set to an instance of an object.
