Spotlight: Troubleshooting - Did they follow the instructions?
Troubleshooting Techniques: Step 1 - Were all the instructions followed correctly?
There was a website of ours that use two Web Logic servers in a cluster for fail over reasons. A lot of our systems work this way. For reasons the main support team couldn't figure out, changes they made to one node in the cluster weren't being propagated to the other node correctly. When they told me they already checked to make sure all the port numbers were set up correctly, I believed them. Big mistake.
After 6 hours on the phone and using NetMeeting to try to diagnose the problem, I finally suggested we start at the beginning and verify the instructions. I should have done that at the start and not trust what I was told because, behold, the port numbers were configured incorrectly because somebody didn't follow the directions correctly. I ought to read through that series every time I get pulled into one of these things to make sure I follow my own advice.