Today, we spent a few hours trying to get my login working into a test system. After about an hour, we found out that rather than being defined in an xml file, they were now in a database and we needed a test app to update the database.
When this change was made, all the developer had to do was to delete/move/rename the XML files in our source control and we would have immediately asked the question as to who and why it was changed. 5 minutes saved by the developer cost 2 man-hours of money to the company.
Also, very simple things like having some basic wiki articles on how to do certain things can save the hassle of asking busy people questions and waiting around for answers. This is especially true of anything that might have subtle non-obvious steps like changing permissions or adding test data to databases.
The first time these things happen, learn from them and adjust. They should not happen a second time!