Not a loop, but...
About 10 years ago I did a piece of work for a council. New Windows 2003 servers, new Active Directory domain from NT4 and a new bunch of Citrix servers.
The servers were all HP ProLiant DL360's and a nice pair of shiny new Cisco switches for them to be plugged into.
We completed all the work and the customer was happy.
A few weeks later, I got a call to say Citrix had ground to a halt.
I'd got an account and RSA token to support them remotely so I duly connected and indeed it was terrible but from the remote session. I couldn't see anything wrong.
Of course, nobody had changed anything...
So I drove all the way to site (a 5+ hour drive). On arrival, I went into the server room, and right there in front of me, two cables came out of the front of server cab from the uplinks on Cisco switches. They went overhead into another cab which held an ancient (even by then) 100Mb half duplex 3Com switch.
Their network manager their had decided for some reason it was needed/a good idea.
I was amazed the lot even ran. But obviously popping them back into their correct switch ports and a reboot later, everything was resolved.
I was somewhat annoyed at the stupidly unnecessarily long drive for that visit .