A month ago I found a bug where installation of the CLICK Extranet 5.5.3 gives bunches of error messages saying it can not find SQL Server when SQL Server 2005 (SS05) is running at the latest version, SP3.  I developed a workaround from their suggestion, and have done a number of installs successfully.

The use of SS05 with CLICK 5.5.3 caused the Windows Installer to run in an infinite loop.  It wastrying to install something unknown over and over.  Microsoft support in India did a great job defining and solving the issue. I posted an issue CLICK's support web site, and they have confirmed it. They even used our solution to help another client.