On this environment all of a sudden we couldn't add users to Active Directory anymore. Also users could not change their password (using my excellent webpart) so I checked what was wrong with the server. It soon became clear that the particular server could not connect to the domain controller. The odd thing was that the domain controller was pingable so the two servers could see each other. When I pinged again a different IP address was returned.. so I pinged again and again and again.. to my surprise every time when I pinged I got a different IP address. The cause of this was a wrong setting in the DNS. The first address was of the proper virtual LAN and then address that was returned came from the 2nd virtual LAN that is only being used for backup procedures. So we asked the infra guys if they could fix this error since this 'glitch' since it was causing more problems as well. One more serious than the first I described like that the database server could not authenticate our service account. And we all know what happens if SharePoint cannot contact the database server..
As soon as that was fixed our intranet environment went down..
After facing some performance issues we followed the guidelines by Joel for Application pools. And well.. just read the post at Sharepoint Application pool settings- update
Short conclusion : check REQUEST QUEUE LIMIT instead of uncheck the damn thing ;)
And then.. when all things were solved we got a call from support that our extranet environment could not accessed through the internet..
Sigh.. I guess it's love / hate thing :)