Invoke or BeginInvoke cannot be called on a control until the window handle has been created.
This issue is happening because of a behavior change in .NET that is exposing an issue with SQL Setup User Interface (UI). The issue will be addressed in the final release of SQL Server 2008 R2.
Typically, if you try to run setup again, you will not see the error. Some people have reported needing to try to run setup three times before the error does not appear.
SQL Server Forums post (http://social.msdn.microsoft.com/Forums/en-US/sqlsetupandupgrade/thread/cd949d50-7d43-48ba-a204-e5ce4f292638)