Here’s another oddity which I stumbled upon recently whilst working on a 64-bit Windows 2003 machine so I thought I’d share it here.
I installed IIS on a newly installed 64-bit Windows 2003 R2 server and needed to configure it to support Asp.Net 1.1 applications. In order to do this I had to configure IIS to run in 32-bit mode as documented in this KB article How to switch between the 32-bit versions of ASP.NET 1.1 and the 64-bit version of ASP.NET 2.0 on a 64-bit version of Windows.
Once I had done this I went back into the Properties of the Default Web Site and I noticed that the ASP.Net tab seemed to have mysteriously vanished. After closing and re-opening and then checking the MMC a few times I still couldn’t find the ASP.Net tab. So I followed the same procedure on another 64-bit Windows 2003 server and got the same results - the Asp.Net tab disappeared after I configured the Enable32bitAppOnWin64 metabase property.