Running two different versions of ASP.NET on the same server

I just installed Orcas and was getting this error when running a performance test:

Event Type: Error
Event Source: ASP.NET 2.0.50727.0
Event Category: None
Event ID: 1062
Date: 5/24/2007
Time: 11:11:12 AM
User: N/A
Description:
It is not possible to run two different versions of ASP.NET in the same IIS process. Please use the IIS Administration Tool to reconfigure your server to run the application in a separate process.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

Running aspnet_regiis -i fixed the issue. You should be all set to run Orcas on new sites you create, but you’ll need to manually set 3.5 for that site.