Visual Studio 2005 SP1 failed with error Installation failed - 0x64C

The error is related to an unsigned driver.

I found an excellent post which explained the steps to take to enable the correct Software Protection Policies at

http://blogs.msdn.com/knom/archive/2007/05/02/problems-with-visual-studio-2005-sp1-on-windows-2003-server.aspx

1) Open local security setting: Start -> Programs -> Administrative Tools -> Local Security Policy.

2) Click on "Software Restriction Policies" and if it shows "No Software Restriction Policies Defined" then insert a new (right click the left pane node).

3) 2 x click on the "Enforcement" entry and under "Apply software restriction policies to the following users:" section change to "All users except local administrators".

He also mentions that he tried placing the original VS2005 disk in the CD tray whilst performing the service pack installation (note that getting MS products to work correctly engenders all kinds of quasi-supernatural beliefs!)

I followed the above steps (including the CD in the tray) and the SP installed correctly.

I also found a bizarre KB article which tells you to remove the .NET framework, then install the SP, then reinstall the framework – don’t bother!