Client's beta testers complain about bugs.
Me: "But we fixed those a week ago and uploaded them to your test server. Why are they reported again?"
Client: "We switched to another test server."
Me: "One week before launch? And you didn't bother telling us?"
Client: "Why is it important to you, you haven't even fixed the old bugs."
Me: "We did fix them. On what used to be your test server up to the switch you didn't tell us about."
Client: "Well, you're the IT guy, I only see the reports of how many open bugs you still have."
I ended up sending back all bug reports as "fixed on old server, please don't report again". One day later, the server switch was reversed and things got back to normal.