SQL Server 2008 R2 Installation Error: '' is not a valid login or you do not have permission.

Problem:

I try to install SQL Server 2008 R2 Developer edition on my 64-bit Acer laptop with Windows 7 Professional and get the above error.

Reason:

The computer name and the user account name is the same and the user account is selected as the default admin in the setup process.

Solution:

Either change the computer name or use a different user account with admin privilege.