The title might seems strange as in 99.99% of cases we cannot afford Visual Studio in production environment. Even hardly mention this possibility could drive sysadmin crazy ;). Last moth Vladi Tchalkov gave a nice presentation on the subject on SofiaDev monthly meeting.
There is another resource on the subject - there is whole guide made by Patterns&Practice team in Microsoft -
Production Debugging for .NET Framework Applications
It could give some nice ideas how to troubleshoot issues in application in production environment.