Reporting Services ASP.NET v1.1 Not Installed

I have finally had an opportunity this morning to re-build my laptop with the RTM of Visual Studio 2005 and SQL Server 2005. One of the interesting things that I have found along the way when installing SQL Server 2000 Reporting Services, is during the “Check Prerequisites” stage I received the error “ASP.NET v1.1 Not Installed” after installing Visual studio 2003 and Visual Studio 2005.  This did not seem quite right as I had just tested that VS 2003 and VS 2005 co-existed happily by building and testing an 2003 ASP.Net application I have been working on.

So I decided to fire up RegMon (http://www.sysinternals.com/Utilities/Regmon.html) to see what the Reporting Services install was checking in the Registry  to determine that “ASP.NET v1.1 Not Installed”.  It turns out that the RS install is checking the version of the ASP.Net using the key [HKLM\SOFTWARE\Microsoft\ASP.NET\RootVer].  The Value for this key was 2.0.50727.42 as a result of installing Framework v2 with VS 2005.  I modified the RootVer value temporarily back to 1.1.4322.573 and the “Check Prerequisites” passed without an issue.