Are you running Exchange 2007 on a VM? Are you experiencing odd warning events in the event log that look something like this?
Event Type: Warning
Event Source: W3SVC-WP
Event Category: None
Event ID: 2262
Time: 12:28:18 PM
ISAPI ‘c:\WINDOWS\Microsoft.NET\Framework64\v2.0.50727\aspnet_isapi.dll’ reported itself as unhealthy for the following reason: ‘Deadlock detected’.
If you’ve answered yes to these questions, you’ve most certainly looked for the fix, and found other users in the same boat. They try and try to fix the issue with adjustments in official documentation or otherwise, with no results.
That was me. …until I ran across this link.
So, as suggested, I added a 2nd vCPU to my exchange server (running on Windows Server 2008 x64, in a vSphere cluster), and started it up. These specific warning messages in my event log went away completely. Okay, after several weeks of monitoring, I may have had a couple of warnings here and there. But that’s it. No longer the hundreds of warnings every day.
As for the official explanation, I don’t have one. Adding vCPU’s to fix problems is not something I want to get in the habit of, but it was an interesting problem, with an interesting solution that was worth sharing.
Microsoft’s most closely related KB article on the issue (that didn’t fix anything for me):
Application pool recycling: