So here I am moving new ASP.NET 3.5 code from QA, where the small changes I made worked fine, to Production, where it fails and shows only "Service Unavailable" on the page. Nothing in the web log. Nothing in the Event Log. I've stopped and started the site, refreshed the web server, and I've even jumped up and down screaming. Nothing helps, and it is completely mysterious to me what is wrong!
The QA server is Windows 2003 running IIS 6, just like the Production server -- but the result is different.
I'm kind of out of ideas, so I am hoping someone here can suggest some.