I have been using an MSI to install a WPF application using the .NET Framework 3.5 SP1. I have set up .NET 3.5 as a prerequisite in the MSI, and what has been happening for ages is that when the user does not have .NET 3.5 SP1, the MSI first has them download and install that before resuming the installation of my application.

Since yesterday when MS released .NET 4.0, when users don't have .net 3.5 SP1, the MSI is directing them to install 4.0 instead. What happens though, is that after they finish installing 4.0, the MSI still detects that they don't have 3.5, and directs them to the 4.0 install site again. So the user has 4.0, but the MSI doesn't ever get to installing my application.

What do I have to change in my application? This seems like an error with how MS is handling the prerequisites either on their server or in the MSI in VS 2008.