Very occasionally errors have been encountered during SQL 2008 install similar to the following:

 

 

This error has been found to be due to corruption in the MS-Windows registry for SQL related keys under the "Components" hive.  Specifically, these key entries have lost their "owner" and consequently their "Permissions".  To fix this, you need to drill down in the registry for each instance of the key indicated in the error message and assign an administrative user as owner, and then add both "System" and "Administrators" groups as Users with full permissions.  This can be a quite time consuming process since some keys can have over 100 instances in the Components hive.

 

References:

 

http://www.intellitechture.com/sql-server-2008-install-nightmare/

http://blogs.msdn.com/b/sqlserverfaq/archive/2010/03/30/sql-server-2008-setup-fails-to-install-with-error-1402.aspx

http://absoblogginlutely.net/2010/04/could-not-open-key-unknowncomponents-fixed/