I worked for a company where they cheaped out on the switch infrastructure and bought low-end Dell switches for the entire network. The kind that don't let you see the MAC address table.

Some guy decided to bring in his Linksys router from home so he could use his laptop and his desktop at the same time (instead of, you know, asking IT to add a second port at his desk). Problem was he left DHCP running on the thing, which obviously led to some confusion. Took forever to find it.

Then again it sounds like the city of 'cisco bough nothing but Cisco gear, so who knows what's really going on here...