There is a known problem with MSI 4.5 that is used by SQL Server 2008 for installing the product. Under some situation the SQL Server 2008 installation will fail with the following error:
"API call rejected - No actions in Context"
Usually rerunning the SQL Server 2008 setup will be fine.
See the following article on how to obtain a fix from Microsoft: http://support.microsoft.com/kb/958655