I was browsing through our production web servers application event logs today and noticed a bunch of errors from .NET 2.0 Runtime Error Reporting about w3wp.exe crashing.  This naturally bothered me being a former systems administrator; it also bothered me because I was afraid that our asp.net application was the source.  After a couple hours of pair troubleshooting, we found that every time our app pool got recycled it was crashing, thus causing a nasty application event log message.  This was caused by the fact we were running our web server as Windows Server 2003 domain controllers.  The fix was to set the proper permissions (Query Value, Set Value, Create Subkey, Enumerate Subkeys, Notify and Read Control) on the following registry key for the Network Service account:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ASP.NET_2.0.50727\Names

For more info see this article: http://channel9.msdn.com/ShowPost.aspx?PostID=215428.