IIS 6 with about 25 sites, one of which is .net framework 2.0 with a .net framework 4.0 app below it running mvc 3 in its own app pool. It runs fine for some time, then we see event 1062 and the .net 4 app won't respond until the app pool is recycled. Every time I've seen 1062 in the past the app won't event come up once - what could be causing this?
It's a race condition. The first one to run wins. You'll need to break the 4.0 app into its own app pool. Here's a writeup on this that I wrote a few years ago, but is still applicable today (for IIS6): http://weblogs.asp.net/owscott/archive/2006/01/26/Running-multiple-versions-of-the-Framework-in-ASP.NET.aspx